Pakistan is multiplying its nuclear arsenal much beyond its present stable of 60 to 100 weapons and increasing their destructive power and deliverability system, according to latest satellite photos released on Wednesday.
Pakistan is expanding its plutonium producing production capacity to build smaller, lighter plutonium-fission weapons and deliverable thermo-nuclear weapons.
The new lighter nuclear weapons would use plutonium as a nuclear trigger and enriched uranium in the secondary, a report by US arms control institute said.
Satellite images have revealed that Pakistan now has the fastest nuclear weapons programme and it has considerably expanded two sites producing fissile material for nuclear weapons, the report by the Institute for Science and International Security (ISIS) said.
The new plutonium producing sites are located near Rawalpindi and could be engaged in activities to build two new plutonium production reactors. Islamabad so far has only uranium-based nuclear weapons.
"Pakistan's ongoing expansion of its plutonium production programme, which includes new undeclared, unsafeguarded reactors and plutonium reprocessing facilities, is likely linked to Pakistan's strategic plans to improve the destructiveness and deliverability of its nuclear arsenal," ISIS said.
The other sites being expanded, according to the satellite photos released by the ISIS, are located near Dera Ghazi Khan in the North West Frontier Province (NWFP), which produces natural uranium hexafluoride (UF6) and uranium material, two materials used for making Pakistan's nuclear weapons.
Satellite photos taken in August last year, of the chemical plants in Dear Ghazi Khan, show new industrial buildings, new anti aircraft installations and several settling ponds that have come up as part of the expansion.
The satellite photos of the expansion of Pakistan's nuclear weapons capability come as top US military commander Admiral Mike Mullen confirmed last week that Pakistan was building up its nuclear arsenal.
With the Pakistani security forces waging a war against militant groups in the NWFP, ISIS said that security of country's 'nuclear assets remains in question'.
"An expansion in nuclear weapons production capabilities, needlessly complicates efforts to improve the security of Pakistani nukes," the report said.
Dera Ghazi Khan nuclear site in the recent past had been a target of at least one ground attack by more than a dozen gunmen, the report said adding that a nearby railway line had also been bombed.
CIA chief Leon Panetta said on Tuesday that US intelligence doesn't have complete track of Pakistani nuclear weapons, but was sure that they were "pretty secure". The US report has urged the American government to prevail upon Pakistan to halt production of fissile material and join talks that would ban production of plutonium and highly enriched uranium.