Top U.S. officials recently made public concerns that Pakistan may be ramping up its nuclear weapons capability, despite a looming civil war. Now we have some visual evidence: Satellite imagery that appears to show the expansion of Pakistan's plutonium production program and a possible increase in stocks of weapons-grade uranium.

Commercial satellite images released today by the Institute for Science and International Security – a very credible source for arms control analysis – appear to underscore Pakistan's determination to increase its supply of fissile material and develop more destructive nuclear weapons. Most worryingly, the report suggests that Pakistan may be on the path to creating thermonuclear weapons that would be more powerful and potentially easier to package in a warhead.

Among the findings: Pakistan appears to have increased its plutonium separation capability at a site near Rawalpindi. According to ISIS, the new construction seems to indicate that Pakistan will be increasing its supply of spent fuel from new heavy water reactors, providing the raw material for separating out fissile plutonium. The country is also apparently expanding a facility at Dera Ghazi Khan that produces uranium hexafluoride and uranium metal, two basic ingredients for producing the bomb.

Ramping up these nuclear facilities, ISIS notes, is "likely linked to a strategic decision to improve the destructiveness and deliverability of its nuclear arsenal." Take, for instance, the focus on plutonium production: A plutonium fission device can be used as the "primary" (i.e., as the trigger) for a staged weapon that would set off a thermonuclear "secondary." That's scary enough; but equally troubling is the potential vulnerability of these nuclear sites.

As ISIS notes, the Dera Ghazi Khan facility, or the nearby workers' compound, "has been the target of at least one ground attack by more than a dozen gunmen, and nearby railway tracks have also been bombed." Those attacks, the report notes, were likely carried out by Baloch separatists, not Taliban extremists, but the attacks underscore Pakistan's fragile state.

[Images: DigitalGlobe/ISIS]

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