Pakistan is enhancing its atomic weapon capabilities across the board by developing and deploying new nuclear-capable missiles and expanding its capacity to produce fissile material, two US experts have said, estimating Islamabad has an arsenal of 70-90 warheads.
In an article published in the latest issue of 'Bulletin of the Atomic Scientist', Robert S Norris and Hans Kristensen estimate that Pakistan's nuclear stockpile has jumped to an estimated 70-90 warheads from a previous figure of 60.
"A new nuclear-capable ballistic missile is being readied for deployment, and two nuclear capable cruise missiles are under development. Two new plutonium production reactors and a second chemical separation facility also are under construction," Norris and Kristensen wrote.
However they agree that it is exceedingly difficult to estimate precisely how many nuclear weapons Pakistan has produced, how many are deployed, and of what types.
"It is equally troublesome to guess what its future plans might be," the article says.
Norris is a Senior Research Associate at the Natural Resources Defense Council while Kristensen is Director, Nuclear Information Project at Federation of American Scientists.
The two US experts believe that Pakistan's nuclear arsenal might not have crossed the 100 figure mark.
Rolf Mowatt-Larssen, ex CIA top official on weapons of mass destruction, noted a more accelerated pace by Pakistan: "It took them roughly 10 years to double the number of nuclear weapons from roughly 50 to 100".
Following the example of other nations that have developed nuclear weapons, Pakistan is improving its weapon designs, moving beyond its first-generation nuclear weapons that relied on highly enriched uranium, the article said.
In anticipation of this increased plutonium production capacity, Pakistan also is expanding its capabilities to reprocess it, it added.
Satellite images show a second under-construction separation facility adjacent to the original that could handle the plutonium produced in the two new Khushab reactors.
"Work also may have resumed on a partially built separation plant that dates from the 1970s. This plant is located at Chasma where Pakistan operates a 300-megawatt commercial reactor (CHASNUPP-1) and plans to build three more, one of which is under construction," it said.
Additionally, Pakistan is expanding its facilities at Dera Ghazi Khan in southern Punjab, where uranium hexafluoride and uranium metal are produced, the article said concluding that all of these efforts suggest that Pakistan is preparing to increase and enhance its nuclear forces.
In particular, the new facilities provide the Pakistani military with several options: fabricating weapons that use plutonium cores, mixing plutonium with HEU to make composite cores and/or using tritium to "boost" warheads' yield, the nuclear experts said.
In the absence of a successful full-scale thermonuclear test, it is premature to suggest that Pakistan is producing
two-stage thermonuclear weapons, they said.
At the same time it noted that the types of facilities under construction suggest that Pakistan has decided to
supplement and perhaps replace its heavy uranium-based weapons with smaller, lighter plutonium-based designs that could be delivered further by ballistic missiles than its current warheads and that could be used in cruise missiles.
Norris and Kristensen said Pakistani Air Force most likely assigns its US-manufactured F-16s a nuclear mission,
though it also could use French-manufactured Mirage Vs.
The weapons storage in Sargodha Air Base, they wrote, has igloos but lacks the extra security features that would
suggest that the base stores nuclear weapons.
"The assembled nuclear bombs and/or bomb components assigned to the F-16s stationed at the base may be kept at the large Sargodha Weapons Storage Complex. Another alternative is that, fearing a first strike by India, Pakistan stores its weapons at operational or satellite bases west of Sargodha, where F-16s could disperse to pick up their bombs," it said.
Pakistan has three types of operational ballistic missiles considered capable of delivering a nuclear warhead
including the short-range ballistic missiles Ghaznavi (Hatf-3) and Shaheen-1 (Hatf-4) and the medium-range Ghauri (Hatf-5).
A fourth missile, the Shaheen-2 (Hatf-6), may soon become operational. Additionally, Pakistan also is developing
two cruise missiles that US Air Force intelligence estimates may be nuclear capable.