Pak has fudged or has lost half its stock: Experts

US experts say they detected only one seismic signature from the tests, although it could have involved multiple devices. The yield of the test was estimated at about 10 kilotons, which would make it much smaller in size than the bomb dropped by the US on Hiroshima which was of 15 kilotons.

If indeed Pakistan used five Hiroshima bomb size devices to conduct five tests, then it would have had to effectively use almost half its inventory of fissile material, experts here say.

“There is some discrepancy here. Either they arefudging the tests or they have fudged production of fissile material,” David Albright, a weapons expert at the Institute of Science and International Security told The Indian Express.

Albright, who has studied the Indian and Pakistani fissile material production closely, estimates that Islamabad had produced about 210 kilogram of bomb grade fissile material till the time they ceased production under US pressure in 1991. Even assuming an error margin of 25 per cent, Pakistan’s fissile material stock would not exceed 300 kg.

For a reasonably successful test, Pakistan would have to use about 20 kg of fissile material per device. Conducting five tests could have used up nearly 100 kg of fissile material.

It is conceivable though, says Albright, that Pakistan used much less material per test or conducted fewer than five tests. It is also possible that like India, Pakistan too has conducted some sub-kiloton tests to make tactical battlefield nuclear weapons. “It would require a degree of skill andsophistication, but it is not impossible,” Albright said.

What is certain is that Pakistan did not test a thermonuclear device (a hydrogen bomb). While Pakistani officials and scientists did not elaborate on the tests, they made no claim about a thermonuclear test.

Pakistan is believed to have resumed production of bomb-grade fissile material about a year back. Its current production capacity is estimated at 110 kg per year. It’s favoured and only available fissile material is highly enriched Uranium (HEU) produced by the centrifuge method at Kahuta.

Experts say Pakistan is also hurrying to produce Plutonium at its new Chasma reactors, although there is no indication yet that it is being made in sufficient quantities. Weapons grade Plutonium will enable Pakistan to make more compact and sophisticated bombs.

Estimates of India’s stockpile of fissile material is in the region of 2,000 kg. New Delhi has said it is ready to join talks on the fissile material cut-off treaty, which will freeze productionof bomb grade material world wide.

Officials here say the Pakistani tests recorded 4.6 on the Richter scale, about the same as the Indian tests, although this is not an indication of how big the bang was (it would also depend on the site and depth of the shaft etc).

The tests were masterminded by A Q Khan, widely known as the father of the Pakistani nuclear programme. It is not yet known if Khan was at the site, but Paksitani media reported he had dispatched two of his senior scientists, Fakharul Hasan Hashmi and Javed Arshad Mirza to the test site.