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Pakistan's Nuclear Weapons Program

1998: The Year of Testing

"Dhamaka kar dein." (Conduct the explosion.)
Prime Minister Mohammad Nawaz Sharif, 18 May 1998
"Today, we have settled a score and have carried out five successful nuclear tests"
Prime Minister Mohammad Nawaz Sharif, 28 May 1998

Last changed 6 August 2001


The re-election of the Bharatiya Janata Party (BJP) to power in India in 1998 was a turning point in world affairs due to its decision to carry out India's first nuclear tests in 24 years. India had been poised on the brink of doing so for some years, with successive governments making active preparations to hold tests, going so far as to actually emplace nuclear devices in test shafts, and - under the first short-lived BJP government - to actually order that tests be conducted. Support for an open declaration of nuclear weapons status had become popular with the Indian public by 1995, and it was an official part of the BJP political platform. The successful execution of nuclear tests under the second BJP government was thus all but a foregone conclusion.

Like India, Pakistan had made many preparations for testing over the years, and could thus organize a test effort on short notice.

On 6 April 1998 Pakistan conducted its first test of the Ghauri. Pakistani media reports credited the missile with a 1100 km test flight and an apogee of 350 km, but information on the impact point shows that the flight distance was no more than 800 km. The system had a claimed range of 1500 km. While Pakistan has stated publicly that the missile was designed and produced indigenously it was, in fact, a North Korea produced No-dong. This was the second test of a No-dong, and it is believed that DPRK observers were present [Bermudez 1998a]. Although this test did not actually influence India's preparations for the tests held 5 weeks later, it did help create the atmosphere of tension in which the tests were conducted.

Ghauri, April 1998
Ghauri Ghauri Ghauri Ghauri Ghauri Ghauri Ghauri

In the afternoon of Monday, 11 May 1998 Indian Prime Minister Atal Behari Vajpayee stunned the world by announcing at a hurriedly convened press conference that earlier that day India had conducted three nuclear tests. International observers were, if anything, even more astonished by the announcement two days later that two additional tests had been conducted.

The Decision to Test

India's test created an untenable situation for Prime Minister Mohammad Nawaz Sharif. In the wake of India's tests, Pakistan felt an urgent need to demonstrate its own prowess in a similar manner for many reasons - to deny India unilateral technical advantage it might have gained from conducting tests; to restore a sense of a balance-of-power with India in the eyes of itself, India, and the world; et cetera. Pressure for test spanned the political spectrum from liberals like opposition leader Benazir Bhutto to the religious right. Bhutto reportedly went so far as to declare that "if there is military capability to eliminate India's nuclear capacity, it should be used." Conservatives within the Sharif administration, particularly Foreign Minister Gohar Ayub Khan pressed very hard for tests. And the Pakistani military, the true seat of power in Pakistan and the actual authority over its nuclear weapons, had been eager to conduct tests for years. Sharif thus faced unbearable pressure to authorize its own nuclear test series. It is very likely that had he refused to go along with tests, Sharif's government would have fallen to a military takeover then and there (rather than 17 months later).

Despite the inevitability of the Pakistani response, it was a strategic disaster. Pakistan had suffered under the penalties of the Pressler Amendment for years. If Pakistan had abjured testing at this point, its status on the world stage would have climbed dramatically - as the "responsible" member of the India-Pakistan confrontation. The symbolic significance of turning the other cheek in the face of India's provocative testing would have made Pakistan the idol of proponents of non-proliferation, and likely would have led to the repeal of the Pressler Amendment sanctions. But by responding in kind, Pakistan not only lost all of these opportunities, it subjected itself to additional sanctions imposed in retaliation.

The day after the first tests Ayub Khan said the Asian subcontinent has been thrust into a nuclear arms race and indicated that Pakistan was ready to conduct a nuclear test of its own. "We are prepared to match India, we have the capability ... We in Pakistan will maintain a balance with India in all fields," he said n an interview. "We are in a headlong arms race on the subcontinent."

Prime Minister Sharif was much more subdued, refusing to say whether a test would be conducted in response: "We are watching the situation and we will take appropriate action with regard to our security," he said.

After returning to the country from a trip to Central Asia on 13 May Sharif met for several hours with senior military officials and senior members of his government to discuss India's action, which appeared to have taken Pakistan's security establishment by surprise. "We didn't have any advance information on these explosions," said a member of Sharif's cabinet.

Another cabinet member said, "Not surprisingly, many ministers thought it was the ideal moment for Pakistan to test its nuclear device," and Pakistan's army informed Sharif that it will be ready "within a week" to conduct an underground nuclear test on 24 hours' notice. But officials familiar the deliberations spoke of a division within the cabinet over an appropriate Pakistani response.

According to an aide, Sharif appeared to favor "a balanced and moderate response" and ordered a report on the cost the country would have to bear if a Pakistani nuclear test brought international sanctions.

The same day President Clinton telephone Sharif and urged him not to go ahead with a test, asking him "not to respond to an irresponsible act in kind."

[Azam 2000] provides an account of the initial cabinet meeting at which Pakistan's response to the Indian tests was considered:

A meeting of the Defence Committee of the Cabinet (DCC) was convened on the morning of 15 May 1998 at the Prime Ministerís Secretariat, Islamabad to discuss the situation arising out of the Indian nuclear tests. The meeting was chaired by the Prime Minister of Pakistan and attended by the Minister of Defence, the Minister of Foreign Affairs, Gohar Ayub Khan, the Minister of Finance & Economic Affairs, Sartaj Aziz, the Foreign Secretary, Shamshad Ahmed Khan and the three Chiefs of Staffs of the Army, Air Force and Navy, namely General Jehangir Karamat, Air Chief Marshal Pervaiz Mehdi Qureshi and Admiral Fasih Bokhari respectively.

Since Dr. Ishfaq Ahmed, Chairman of the PAEC was on a visit to the United States and Canada the responsibility of giving a technical assessment of the Indian nuclear tests and Pakistanís preparedness to give a matching response to India fell on the shoulders of Dr. Samar Mubarakmand, Member (Technical), PAEC. Dr. Mubarakmand was in charge of the PAECís Directorate of Technical Development (DTD), one of the most secretive organizations in the Pakistan nuclear programme the location of which is one of Pakistanís best kept secrets and unknown to the world. Dr. Mubarakmand had supervised several cold tests since 1983 and was responsible for overseeing all of PAECís classified projects. Also, in attendance was Dr. A.Q. Khan, Director of the Khan Research Laboratories (KRL), Kahuta.

There were two points on the DCCís agenda: Firstly, whether or not Pakistan should carry out nuclear tests in order to respond to Indianís nuclear tests? Secondly, if Pakistan does go ahead with the tests then which of the two organizations, PAEC or KRL, should carry out the tests?

The discussions went on for a few hours and encompassed the financial, diplomatic, military, strategic and national security concerns. Finance Minister Sartaj Aziz was the only person who opposed the tests on financial grounds due to the economic recession, the low foreign exchange reserves of the country and the effect of inevitable economic sanctions which would be imposed on Pakistan if it carried out the tests. Prime Minister Nawaz Sharif neither opposed nor proposed the tests. The remainder spoke in favour of conducting the tests.

Dr. Mubarakmand gave a technical assessment on behalf of the PAEC of India's tests. Unsuprisingly, given the outside skepticism about India's test claims and India and Pakistan's mutual habit of denigrating each other's ability, his assessment was that there had been only one successful test on 11 May, and if a thermonuclear device had been fired then it had been a failure. Mubarakmand added that if it is decided that Pakistan should go ahead with nuclear tests of its own, then the PAEC is fully prepared to carry out the nuclear tests within 10 days.

[Azam 2000] continues:

Dr. A.Q. Khan, speaking on behalf of KRL, also asserted that KRL was fully prepared and capable of carrying out nuclear tests within 10 days if the orders are given by the DCC. Dr. Khan reminded the DCC that it was KRL which first enriched uranium, converted it into metal, machined it into semi-spheres of metal and designed their own atomic bomb and carried out cold tests on their own. All this was achieved without any help from PAEC. He said that KRL was fully independent in the nuclear field. Dr. Khan went on to say that since it was KRL which first made inroads into the nuclear field for Pakistan, it should be given the honour of carrying out Pakistanís first nuclear tests and it would feel let down if it wasnít conferred the privilege of doing so.

Thus, both the PAEC and KRL were equal to the task. However, PAEC had two additional advantages which KRL didnít. Firstly, it was PAEC which had constructed Pakistanís nuclear test site at Chagai, Baluchistan. Secondly, PAEC had greater experience in conducting cold tests than KRL.

The DCC meeting concluded without any resolution of the two agenda points.

By week's end American spy satellites had detected an influx of equipment at a previously prepared test site in the Chagai Hills in the desert of southwestern Baluchistan province, barely 50 km from the border with Iran, and the CIA was predicting that a test could occur as early as Sunday 17 May.

Over the weekend Sharif consulted with various parties and factions, and remained under enormous pressure to test. Meanwhile public reaction continued to favor an immediate response. Former PM Benazir Bhutto advocated not only an immediate nuclear test by Pakistan, but also asserted that India should be disarmed by a preemptive attack, and called on Sharif to resign.

The tension was ratcheted up on Saturday by Ayub Khan, known to be a hard-liner with close ties to the military, when he remarked to reporters that a nuclear test by Pakistan "is just a matter of timing and the government of Pakistan will choose as to when to conduct the test." "A nuclear test by Pakistan is certain," he added.

Aub Khan repeated the remarks the next day, telling The Associated Press that Pakistan has decided to go ahead with a test of a nuclear device. "It's a matter of when, not if, Pakistan will test," he said. "The decision has already been taken by Cabinet," he said in a telephone interview from his rural home in northwestern Pakistan.

The frenzy of speculation reached a peak on Sunday, 17 May, when the nuclear device was believed to be in place for a test. There was even a brief flurry of excitement caused by a false alarm on Sunday when German President Helmut Kohl said he had "reliable information" saying Pakistan had exploded a bomb, a report that was quickly denied and discredited.

The Chairman of the PAEC, Dr. Ishfaq Ahmed, cut short a foreign trip and returned to Pakistan on 16 May 1998. On the morning of 17 May 1998, he received a call from the Pakistan Army GHQ, Rawalpindi informing him to remain on stand-by for a meeting with the Prime Minister. He was thereafter summoned and, accompanied by Dr. Mubarakmand, met with Sharif at his official residence. Sharif asked the PAEC Chairman for his opinion on the two points which were discussed in the DCC meeting the day before. Ahmed assured the Prime Minister that the PAEC was ready to test when ordered to do so, but declined to take a position on whether the order should be given. At conclusion of the meeting he was told to prepare for the tests but remain on stand-by for the final decision [Azam 2000].

According to [Azam 2000]:

Since the DCC meeting of 15 May 1998 proved inconclusive, it is believed that a more exclusive DCC meeting was held on 16 or 17 May 1998 attended only by the Prime Minister, the Foreign Minister, the Finance Minister and the three Chiefs of Staff of the Army, Air Force and Navy. This meeting has never been officially acknowledged but it must have been held as neither the Prime Minister alone nor the Chief of the Army Staff alone could have made the decision to conduct the nuclear tests. The DCC was the only competent authority to decide on this matter, especially since the National Command Authority (NCA), Pakistanís nuclear command and control authority for its strategic forces, did not exist at that time. In this meeting, the two agenda points of the DCC meeting of 15 May 1998 were decided. Firstly, Pakistan would give a matching and befitting response to India by conducting nuclear tests of its own. Secondly, the task would be assigned to the Pakistan Atomic Energy Commission (PAEC), who were the best equipped and most experienced to carry out the tests.

Meanwhile the US worked on putting together an incentive package to Pakistan to persuade it not to test. The repeal of the Pressler amendment that cut off military aid was offered, as was delivery of $600 million dollars worth of F-16 fighter-bombers that Pakistan had ordered and paid for but never received. Discussions also began on how much aid to offer Pakistan on top of these concessions. The automatic imposition of a nearly complete embargo like that imposed on India, but which much smaller Pakistan could hardly afford, provided the penalty side of the equation.

But PM Sharif did not confirm the comments by Ayub, and by the beginning of the next week, Pakistan appeared to have backed off any immediate decision to test, and was content to see how much in aid the US might offer in return.

But out of the public eye things wer moving rapidly in a different direction.

On 18 May 1998, the Chairman of the PAEC was again summoned to the Prime Minister House where he was relayed the decision of the DCC. "Dhamaka kar dein" (Conduct the explosion) were the exact words used by the Prime Minister to inform him of the Governmentís decision to conduct the nuclear tests. The PAEC Chairman went back to his office and gave orders to his staff to prepare for the tests. Simultaneously, GHQ and Air Headquarters issued orders to the relevant quarters in 12 Corps, Quetta, the National Logistics Cell (NLC), the Army Aviation Corps and No. 6 (Air Transport Support) Squadron respectively to extend the necessary support to the PAEC in this regard. The Civil Aviation Authority (CAA) also directed the national airline, PIA, to make available a Boeing 737 passenger aircraft at short notice for the ferrying of PAEC officials, scientists, engineers and technicians to Baluchistan.
[Azam 2000]

Test Preparations

True to form, when news reached A.Q. Khan that the task of testing a nuclear device had been assigned to PAEC, not KRL, he lodged a strong protest with the Chief of Army Staff, General Jehangir Karamat. The Army Chief, in turn, called the Prime Minister. To mollify Khan, it was decided that KRL personnel would be involved in the final preparation of the nuclear test site alongside those of PAEC as well as being present at the time of the test [Azam 2000].

PAEC held a planning meeting chaired by Dr. Ahmed with Mubarakmand and other scientists and engineers of the PAEC in attendance. According to Azam, which devices to test were discussed, and:

It was decided that since the Indian nuclear tests had given an opportunity to Pakistan to conduct nuclear tests after 14 years of conducting only cold tests, the maximum benefit should be derived from this opportunity. It was, therefore, decided, that multiple tests would be carried out of varying yields as well as the live testing of the triggering mechanisms. Since the tunnel at the Ras Koh Hills had the capability to conduct six tests, therefore, six different nuclear devices of varying designs, sizes and yields were selected, all of which had been previously cold tested.

Immediately afterwards, began the process of fitness and quality checks of the various components of the nuclear devices and the testing equipment. A large but smooth logistics operation also got underway with the help of the Pakistan Army and Air Force. This operation involved moving men and equipment as well as the nuclear devices to the Ras Koh test site from various parts of the country.

There are some plausibility problems with this account. The first issue is that successfully collecting data from an actual nuclear test (an area in which Pakistan had no experience despite years of cold tests) is far from straightforward (see [Teller et al 1968; pp. 150, 167]), and increases in difficulty with multiple tests in a single shaft. Unexpected device behavior or problems anywhere along the tunnel could result in the loss of data on any or all shots. If internal telemetry failed, wholly or in part, it would be very difficult to recover useful results from external seismic measurements with so many devices simultanenously exploded so close together. Six devices constituted a large part of the then available highly enriched uranium, perhaps 90 kg consumed out of 210 kg on hand (although once it had spent a couple of years processing its stockpile of low enriched uranium, this would rise to 800 kg or so). A great deal of Pakistan's immediate nuclear resources would be consumed for quite a gamble on useful results.

Other problems include that according to post-test statements, all of these device were of basically the same type - fusion boosted fission bombs. Further four of the device were all in the same low yield range (fraction kiloton to a few kilotons), far less than the tens of kilotons claimed for the other two. It is questionable that so many different systems of this type could be usefully tested. Due to the extensive cold testing, the non-nuclear behavior of these systems should have been well understood and thus variations purely in the implosion assembly design would not merit nuclear testing. By exploding them all once (and the last test only a few days later) there would be no opportunity to analyze the test results and conduct retests, or tests of redesigns.

It is also difficult to credit the implication that such an extraordinarily complex test operation was planned and conducted in 10 days. Admittedly, the preparations for tests dated back years (decades!) so that the test equipment would already be on hand, and the basic procedures would have already have been worked out. Nonetheless, there is a big difference in complexity between a one device test, and a five device test, and it is hard to believe that such an operation could be successfully assembled and executed in such a short time without any prior test experience.

Part of the explanation is no doubt that the numerous tunnel fired cold tests were, or at least could be made to be, pretty fair simulations of actual nuclear test exercises. (At least up to the point of data collection - no amount of cold testing can verify the proper behavior of instruments intended to collect data from an energy density and energy output regime a million times higher.) Also the mobilization of test activity immediately after the first Indian tests, detected by U.S. intelligence, indicates that Azam may be wrong - that the planning for the test exercise was conducted much earlier, even before the Indian test, and these previously layed plans were simply being put into operation. Even if not, test preparations clearly began immediately, and thus had an additional week to be successfully concluded. It is significant that the observed preparation activity began a week before Prime Minister Sharif authorized tests, and suggests that the testing activity may have been not entirely under his control.

The tunnel under Koh Kambaran was 1 kilometer long and is described as L-shaped (just as the Indian vertical shafts were L-shaped). The reason for this is that the shaft leading to the entrance is thus shielded from the device detonation, and energy cannot propagate straight up the shaft from the device to the entrance. The description of the tunnel has having separate assembly rooms indicates that in addition to the L-tunnel at the end, the main tunnel had a number of other side tunnels branching off it every couple of hundred meters.

On 19 May 1998, two teams of 140 PAEC scientists, engineers and technicians left for Chagai, Baluchistan on two separate PIA Boeing 737 flights. Also on board were teams from the Wah Group, the Theoretical Group, the Directorate of Technical Development (DTD) and the Diagnostics Group. Some of the men and equipment were transported via road using NLC trucks escorted by the members of the Special Services Group (SSG), the elite commando force of the Pakistan Army.
[Azam 2000]

According to the Azam the nuclear devices - in sub-assembly form - were flown from Rawalpindi to a designated airfield in Baluchistan (Quetta?) on a Pakistan Air Force (PAF) C-130 Hercules transport aircraft (it is curious that so many would all be entrusted to a single aircraft though). Four PAF F-16s armed with air-to-air missiles provided escort, with secret orders to shoot the C-130 down if it tried to fly out of Pakistani airspace. The F-16s were ordered to keep their radio communications equipment turned off so that no orders, in the interim, could be conveyed to them to act otherwise. They were also ordered to ignore any orders to the contrary that got through to them during the duration of the flight even if such orders originated from Air Headquarters.

The nuclear devices were assembled separately at the test site in individual assembly rooms ("zero rooms") located along the one kilometer tunnel under the mountain Koh Kambaran in the Ras Koh range. Azam states that Samar Mubarakmand personally supervised the complete assembly of all five nuclear devices (implying a very lengthy assembly process since it would have to be sequential, probably lasting more than a day). Diagnostic cables were then laid through the tunnel, and out of the tunnel to the telemetry station which communicated with the command/observation post 10 km away. Afterwards, a complete simulated test was carried out by tele-command. This process of preparing the nuclear devices and laying of the cables and the establishment of the fully functional command and observation post took 5 days (i.e. until about 24 May).

On 25 May it was reported by the Associated Press and Reuters that U.S. intelligence officials had said that Pakistani preparations had accelerated in recent days at a site called Raskoh in the Chagai Hills (it later transpired that Ras Koh was indeed the test area, but Ras Koh is a separate mountainous area over 40 km from the Chagai Hills area). Tunneling activities and the setup of explosive monitoring equipment had been observed. "At this point, they could conduct a nuclear test at any time," said one official.

At the same time it had become increasingly likely that any U.S. aid package would fall short of Pakistani expectations. The major inducements suggested at this point - the delivery of 28 F-16s that Pakistan has already paid for and was promised by Pres. Clinton two years ago anyway, and the rescheduling of loans - was not very tempting. Pakistan seemed to be after explicit U.S. security guarantees, something that was unlikely to be offered.

The test tunnel was sealed by the Pakistan Army 5 Corp on 25 May with the assistance and supervision of the Pakistan Army Engineering Corps, the Frontier Works Organisation (FWO) and the Special Development Works (SDW) - a military unit created 20 years earlier specifically to carry out field engineering for nuclear tests. Mubarakmand is said to have walked a total of 5 kilometers along the stuffy tunnels checking and rechecking the devices and the cables before the cables were finally plugged into the nuclear devices. Sealing the tunnel consumed 6,000 bags of cement and was completed by the afternoon of 26 May 1998. 24 hours later the cement had set in the desert heat, and the engineers certified that the site was ready. The fact the tests were ready was relayed to the Prime Minister via General Headquarters.

Late in the day on 27 May the U.S. government reported that Pakistan had been observed pouring cement in a test shaft in the Chagai Hills. This indicated that nuclear test devices were being sealed in, which is the final necessary step before conducting nuclear tests. Officials then predicted that tests could occur within hours.

Pres. Bill Clinton made a last-minute plea to Sharif, Wednesday night. According to presidential spokesman Mike McCurry it was a "very intense" 25-minute call in which the president implored the prime minister not to conduct a test. It was the fourth presidential call to Sharif since India's first explosion on May 11. But the test time had been set - 3:00 p.m. in the afternoon of 28 May 1998.

The Test is Fired

In the pre-dawn hours of 28 May Pakistan cut the communication links for all Pakistani seismic stations to the outside world. All military and strategic installations in Pakistan were put on alert, and the Pakistan Air Force F-16A and F-7MP air defence fighters were placed on strip alert - ready to begin their take-off roll at any moment.

Azam provides a detailed account of the events that day:

At Chagai, it was a clear day. Bright and sunny without a cloud in sight. All personnel, civil and military were evacuated from ĎGround Zeroí except for members of the Diagnostics Group and the firing team. They had been involved in digging out and removing some equipment lying there since 1978.

Ten members of the team reached the Observation Post (OP) located 10-kilometres away from Ground Zero. The firing equipment was checked at 1:30 p.m. and prayers were offered. An hour later, at 2:30 p.m., a Pakistan Army helicopter carrying the team of observers including PAEC Chairman, Dr. Ishfaq Ahmed, KRL Director, Dr. A.Q. Khan, and four other scientists from KRL including Dr. Fakhr Hashmi, Dr. Javed Ashraf Mirza, Dr. M. Nasim Khan and S. Mansoor Ahmed arrived at the site. Also accompanying them was a Pakistan Army team headed by General Zulfikar Ali, Chief of the Combat Division.

At 3:00 p.m. a truck carrying the last of the personnel and soldiers involved in the site preparations passed by the OP. Soon afterwards, the all-clear was given to conduct the test as the site had been fully evacuated.

Amongst the 20 men present, one young man, Muhammad Arshad, the Chief Scientific Officer, who had designed the triggering mechanism, was selected to push the button. He was asked to recite "All praise be to Allah" and push the button. At exactly 3:16 p.m. the button was pushed and Muhammad Arshad stepped from obscurity into history.

As soon as the button was pushed, the control system was taken over by computer. The signal was passed through the airlink initiating six steps in the firing sequence while at the same time bypassing, one after the other, each of the security systems put in place to prevent accidental detonation. Each step was confirmed by the computer, switching on power supplies for each stage. On the last leg of the sequence, the high voltage power supply responsible for detonating the nuclear devices was activated.

As the firing sequence passed through each level and shut down the safety switches and activating the power supply, each and every step was being recorded by the computer via the telemetry which is an apparatus for recording reading of an instrument and transmitting them via radio. A radiation-hardened television camera with special lenses recorded the outer surface of the mountain.

The voltage reached the triggers on all five devices simultaneously in all the explosive lenses with microsecond synchronization.

As the firing sequence continued through its stages, 20 pairs of eyes were glued on the mountain 10 kilometres away. There was deafening silence within and outside of the OP.

A short while after the button was pushed, the earth in and around the Ras Koh Hills trembled. The OP vibrated as smoke and dust burst out through the five points where the nuclear devices were located. The mountain shook and changed colour as the dust of thousands of years was dislodged from its surface. Its black granite rock turning white as de-oxidisation from the radioactive nuclear forces operating from within. A Huge cloud of beige dust then enveloped the mountain.

The time-frame, from the moment when the button was pushed to the moment the detonations inside the mountain took place, was thirty seconds. For those in the OP, watching in pin-drop silence with their eyes focused on the mountain, those thirty seconds were the longest in their lives. It was the culmination of a journey which started over 20 years ago. It was the moment of truth and triumph against heavy odds, trials and tribulations. At the end of those thirty seconds lay Pakistanís date with destiny.

The Pakistani Ministry of Foreign Affairs would later describe it as "Pakistanís finest hour". Pakistan had become the worldís 7th nuclear power and the first nuclear weapons state in the Islamic World.

The Announcement

Sharif announcing the tests

Sharif announcing the tests

Sharif announcing the tests
Click for larger image

Prime Minister Mohammad Nawaz Sharif
announcing that Pakistan had conducted
five nuclear tests.

On 28 May at 15:00 UCT Prime Minister Sharif began his televised address (pre-announced four hours before) with the statement:

"Today, we have settled a score and have carried out five successful nuclear tests."
In a later address to Pakistani and foreign reporters, Sharif said:
"Pakistan today successfully conducted five nuclear tests. The results were as expected. There was no release of radioactivity. I congratulate all Pakistani scientists, engineers and technicians for their dedicateSmard team work and expertise in mastering complex and advanced technologies. The entire nation takes justifiable pride in the accomplishments of the Pakistan Atomic Energy Commission, Dr. A.Q. Khan Research Laboratories and all affiliated Organizations... Our security, and the peace and stability of the entire region, was gravely threatened. As any self-respecting nation, we had no choice left for us. Our hand was forced by the present Indian leadership's reckless actions. We could not ignore the magnitude of the threat... Under no circumstances would the Pakistani nation compromise on matters pertaining to its life and existence. Our decision to exercise the nuclear option has been taken in the interest of national self-defence. These weapons are to deter aggression, whether nuclear or conventional."
See the complete text of the address.

Seismic readings indicate a detonation time of 10:16:17.6 UCT (+/- 0.31 sec). See the preliminary seismic data, and the official announcement from the Pakistan government web site.

One interesting and significant aspect of this address is the order chosen for Sharif's congratulation of the organizations responsible. The organization chiefly responsible for the development of the nuclear devices, and the tests, was the Pakistan Atomic Energy Commission (PAEC) not the better known Khan Research Laboratories (KRL).

Another interest, and possible significant, fact is the that the initial reports issuing from Pakistan between the time of the tests and Sharif's official announcement indicated that Pakistan had conducted two tests, not five. As discussed below, two is a much more plausible number of devices to have been conducted in a single shaft simultaneous test, especially for a nation with no prior test experience and limited amounts of weapon material.

The extreme tension pervading Pakistan at the time of the tests is illustrated by the fact that five hours after Sharif's announcement (as reported by Agence France Presse), Pakistan summoned the Indian high commissioner to the foreign office and informed him that "credible information" had been received that an attack was to be mounted before dawn on Pakistan's nuclear installations by India, and that "swift and massive retaliation" would result. The ambassador, Satish Chandar, was asked to convey to New Delhi that Islamabad "expected the Indian government to desist from any irresponsible act."

Shortly afterward President Rafiq Tarar issued a terse announcement declaring a state of emergency and suspension of fundamental rights in Pakistan citing threats of unspecified "external aggression."

The Tests

The location of the first Pakistani test was measured seismically by the Comprehensive Test Ban Treaty (CTBT) Prototype International Data Center (PIDC) as occurring at 10:16:17.6 UCT (+/- 0.31 sec) in an elliptical region centered at 28.9032N 64.8933E with major and minor axes of 10.4 km and 8.4 km, with an azimuth of 178 deg. This places the test site in the Chagai District of Baluchistan Province in western Pakistan. The US Geological Survey National Earthquake Information Center (USGS NEIC, usually cited as either "USGS" or "NEIC") data (28.950N 64.720E) had a center offset to the northeast by 20 km, and a time of occurrence of 10:16:15.8 UCT. The preliminary seismic body wave magnitude (mb) for the shot was 4.8 from the PIDC and 4.9 for the USGS (4.8 is cited in [Walter et al 1998]).

The precise location of the Pakistani tests were initially a matter of some uncertainty. The seismic data published by the PIDC and the US Geological Survey (USGS) defined regions that did not contain terrain of the high relief shown by Pakistan Television coverage of the shot. News coverage initially placed the location in the Chagai Hills area, some 40 km from the general area indicated by the seismic data and also lacking high relief terrain. This problem was solved by Certified Mapping Scientist Frank Pabian by correlating publicly available data. Video footage of the test shot being fired, and analysis of the sun shadows, provided the correct azimuthal orientation of the geologic features and the test shaft entrance relative to them. By searching satellite imagery for features that matched those seen in the videos, Pabian located the likely test area and confirmed it by obtaining post-shot satellite images which revealed the test equipment, and the surface displacements caused by the rock slides set off the shot.

The location of the shot turned out to be located in the Ras Koh Hills about 14 km east-southeast of the location centers given by the PIDC and USGS seismic data (and about 9 km outside of the calculated PIDC uncertainty ellipse). The immediate area of the shot was a mountainous region called the Koh Kambaran massif. It had been conducted in a horizontal tunnel bored into the south eastern flank of the principal mountain in the area that rises to 2700 m. The precise geographic location was shown to be location 28 deg 47 min 31 sec N, 64 deg 56 min 51 sec E (+/- 10 sec) or 28.7919N 64.9475E (+/- 0.003) in decimal degrees; the uncertainty corresponds to a distance of 300 m. According to Pakistani reports (confirmed by imagery analysis), the principal explosion was conducted 1 km from the tunnel portal under the mountain [Pabian 1999].

Chagai Region Chagai Region
Images of the Chagai Region

The PIDC originally assigned the event the ID number EVENT 1440477, but changed it to "EVENT 1440562" when subjected to manual analysis. The seismic data from the 1998 tests can be accessed from the IDC web site, the tests are summarized with a map here. Also see the BGR Hannover Seismic Data Analysis Center for a nice summary of the seismic data with a map. The preliminary seismic data form the International Data Centre, which was generated automatically is in this file, while the expert evaluated data prepared five days later is here.

The second test was fired two days later, on 30 May 1998. The PIDC has assigned it an event ID of 1442998. Official Pakistani sources give the time of the shot as 06:55:00.0 UCT, estimated times are 06:54:57.1 UCT (PIDC) and 06:54:56.1 (USGS). The estimated locations are 28.494N 63.781E (PIDC) and 28.720N 64.020E (USGS). Both the PIDC and USGS location determinations are known to be imprecise because they are computed directly from the seismic signals using a globally averaged seismic velocity model (the PIDC uses the IASPEI-91 model) which does not include small regional velocity variations. A more accurate estimate can be obtained using historical seismic data as reference, and calculating an offset (called a Joint Epicentral Determination or JED). A JED calculation for the 30 May event gives a location of 28.433N 63.860E and reduces the error ellipse from 336 km2 to 80 (in addition to correcting for systematic biases) [Barker et al 1998]. Wallace performed a similar Joint Hypocenter Determination (JHD) and obtained a shot time 06:54:57.1 UCT and a location of 28.499N 63.741E ([Wallace 1998] or go to his on-line reprint). See also the BGR Hannover Seismic Data Analysis Center map. Seismic magnitude reported by the USGS for the 30 May event was mb 4.6 [Walter et al 1998]. The JED and JHD locations put the event in a region of low relief topography, especially compared to the May 28 event. This is consistent with remarks by Pakistan's Foreign Minister Gohar Khan about the May 30 test: "The previous ones were in hard rock, but these were conducted in a shaft like a well."

According to Wallace [Wallace 1998] an appropriate formula for the magnitude-to-yield relation in the Chagai district of Pakistan is:

Eq. 1 mb = 4.10 + 0.75 log Y
This formula gives yield estimates of 8-12 kt for the 28 May shot and 4-6 kt for the 30 May shot. Barker et al [Barker et al 1998; p. 1968] also assigned yields of 9 kt (95% c.i. 6-13 kt) for the 28 May and 4 kt (95% c.i. 2-8 kt) for the 30 May shots. Walter suggests a tentative estimate range of 5-20 kt for 28 May, and 3-11 kt for the 30 May shot [Walter et al 1998].

Time:10:16:15.8 28 May 1998 (UCT) USGS;
10:16:17.6 UCT (PIDC)
Location:Ras Koh mountains, Chagai District,
Baluchistan Province, Pakistan
28.7919 deg N, 64.9475 deg E
Test Height and Type:Multiple device (5?, 2?) in underground
horizontal tunnel, 1000 m long
Yield:approx. 9 kt (5-20 kt possible range;
claimed yields range from 18 kt to 40 kt)
According to the well connected but unreliable A.Q. Khan this test group consisted of one large device with a yield of about 30-35 kt and four smaller devices.

Pakistan-I Test Pakistan-I Test, click for larger size
Dust raised on Koh Kambaran in the Ras Koh mountains
by the Pakistan-I test, 28 May 1998

On 31 May, the day after the second test, the test team flew into the capital of Islamabad from Baluchistan Province in a special C-130 aircraft of the Pakistan Air Force (PAF). Pakistan Atomic Energy Commission (PAEC) Chairman Ishfaq Ahmed Khan, PAF officials and staff from NDC and KRL received the team. Dr. Samar Mubarakmand (aka Mubarak, Mubarik, Mobarak, Mubarik Mand, Mobarak Mand, Mubarik Mund, Mobarakmand, Mubarrakmand, etc., etc.) Director General of the PAEC National Development Complex (NDC) who led the test team was the chief recipient of the congratulations. Along with Mubarakmand, senior scientists Dr. Tariq Salija and Dr. Irfan Burney were the key members of the team - responsible for both developing and testing the devices.

"I congratulate the entire nation - We owe our success to their prayers and support," said a heavily garlanded Mubarakmand said in his brief talk to the enthusiastic crowd.

"It is the outcome of team work, who worked dedicatedly day and night to come up to the expectations of the nation."

The achievement, he said, "reflects the professional competence of the Pakistani engineers who in a short time accomplished the task."

Later talking to the newsmen, Mubarakmand said, "we accomplished the given task in a matter of about eight days only."

He was appreciative of his team of scientists, engineers and technicians who made the mission a success. He said, a team of around 150 scientists worked at Chagai.

According to the Associated Press of Pakistan, a senior scientist, who arrived with Mubarakmand said "we got the expected results." He said, "the team stayed at the test site for 8-10 days and worked in excruciating temperatures, ranging up to 53 degrees Celsius.

Another scientist requesting anonymity said that Pakistan had undertaken cold tests, but now it had access to more data to serve as a reference in going ahead with computer simulations for newer designs and types of nuclear devices. He attributed the success to the "stringent quality control" and said it was one of the basic reasons that no test failed.

Describing the differences between the test of a nuclear device and its weaponized version, the head of another section said, "the weaponized versions are more rugged and can withstand, high velocity, extreme temperatures and vibration, whereas the nuclear devices comprise the same material, but which remains in a static state."

Pakistani scientists
The Pakistani scientists posing with a nice view of Koh Kambaran in
the background. The 28 May shot was fired in a tunnel bored
underneath this mountain. The principal scientists responsible for
developing the devices and conducting the tests were the team leader
Dr. Samar Mubarakmand (right of the man in the blue beret) and
Dr. Tariq Salija and Dr. Irfan Burney, all of the PAEC. The better
known A.Q. Khan of KRL is left of the man in the beret (who may be
General Zulfikar Ali, the ranking military officer present).

It is interesting to note that [Azam 2000] cites an incorrect height for
Koh Kambaran of 185 m. Comparing the prominent white band on
the mountain, which satellite photography shows is 520 m long, to this
photograph shows that is over 500 m high.

Pakistani scientists
Pakistani scientists. A.Q. Khan is present, but not
Samar Mubarakmand. Perhaps this is the representation from KRL.

AQ Khan in the tunnel
A. Q. Khan posing in the test tunnel. The test director,
Dr. Samar Mubarakmand, was probably too busy to pose.

Initial reports coming out of Pakistan during the four hour and forty five minute gap between the test and Sharif's official announcement indicated that two test devices had been fired in this shot. Sharif however claimed that five had been fired. There are several reasons to find this claim improbable. Every fission device requires a certain minimum amount of material, no matter how small the yield. Testing five devices at once expended quite a lot of the fissile material available at the time. Furthermore testing multiple devices in a single shaft, and successfully collecting test data, is a technical challenge, a challenge that increases with the number of devices. Even after years of testing experience, and enormous resources, the US has not infrequently experienced failures in test data collection. Placing so many devices in one shaft would run a serious risk that the data from all of the tests would be lost, and thus the fissile material expended with negligible result. India in contrast tested all five of the devices they fired in 1998 in separate shafts. Given the relatively low total yield, most of the devices must have had quite a low yield. It is questionable that Pakistan would have a need to test so many different devices all in the same low yield range.

It can be conjectured that the initial statements of two devices were correct and made by parties knowledgeable about the tests, but not about official policy perhaps even then being formulated by Sharif and his advisers. The reason then that Pakistan officially claimed five devices in this first shot was for status and image reasons, to establish equality in testing with India.

Time:06:55:00.0 30 May 1998 UCT (Pakistani Government);
06:54:57.1 UCT (calculated JHD estimate)
Location:Chagai District, Baluchistan Province, Pakistan
28.433 deg N 63.860 deg E (Barker),
28.499 deg N 63.741 deg E (Wallace)
Test Height and Type:Underground vertical shaft, 1 device (2?)
Yield:4-6 kt est. (3-11 kt max range; 18 kt claimed)

According to Azam: "Pakistan conducted its sixth nuclear test at Kharan, a flat desert valley 150 km to the south of the Ras Koh Hills. This was a miniaturized device giving a yield which was 60% of the first tests. A small hillock now rises in what used to be flat desert, marking the ground zero of the nuclear test there."

Read Khan's interview
with The News given after
the tests.

This test also was plagued by questions of how many devices had actually been fired. Official Pakistani sources broke the news of two tests, and the official Associated Press of Pakistan news agency also carried the news, quoting "authentic" sources. "Yes by the grace of God," Foreign Minister Gohar Ayub Khan told Reuters when asked if reports of two more nuclear tests on Saturday were correct. But the official government announcement by Foreign Secretary Shamshad Ahmed announced one test during a press conference, triggering a barrage of queries from surprised journalists. Intrigued by Ahmed's announcement, they asked him whether they should believe him or other officials.

"All I can say is that I am answering here for the government of Pakistan," the foreign secretary told a questioner who said Foreign Minister Gohar Ayub Khan had confirmed two explosions. Special editions of local newspapers, quoting defense officials, also carried news of two blasts.

In an interview on 30 May 1998 A. Q. Khan told the prominent Islamabad daily The News that the five tests were "all boosted fission devices using uranium 235" but said that although "none of these explosions were thermonuclear, we are doing research and can do a fusion test if asked. But it depends on the circumstances, political situation and the decision of the government." Khan said that of Pakistan's five tests, the first was a "big bomb" which had a yield of about 30-35 kilotons. "The other four were small tactical weapons of low yield. Tipped on small missiles, they can be used in the battlefield against concentrations of troops," he told the newspaper. "This has been a successful nuclear explosion by all definitions. It was exactly as we had planned and the results were as good as we were hoping," he said.

The Pakistan Atomic Energy Commission (PAEC) released a statement saying the five blasts measured 5.0 degrees on the Richter Scale, and produced a yield of up to 40 kilotons of TNT. "These boosted devices are like a half way stage towards a thermonuclear bomb. They use elements of the thermonuclear process, and are effectively stronger Atom bombs," Munir Ahmad Khan, former PAEC director, told Agence France-Presse. Khan said Pakistan has had a nuclear capability since 1984 and all the Pakistani devices were made with enriched uranium.

This was prepared using materials provided by the Indian, Pakistani, and United States governments, by the Associated Press, Reuters, Agence France-Presse, The Times of India News Service, The Washington Post, The Los Angeles Times, The New York Times, the Associated Press of Pakistan, the Press Trust of India, Science News, the Federation of American Scientists, and the High Energy Weapons Archive.

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