Inside the Obama administration, some officials say, Pakistan’s drive to spend heavily on new nuclear arms has been a source of growing concern, because the country is producing more nuclear material at a time when Washington is increasingly focused on trying to assure the security of an arsenal of 80 to 100 weapons so that they will never fall into the hands of Islamic insurgents.

The administration’s effort is complicated by the fact that Pakistan is producing an unknown amount of new bomb-grade uranium and, once a series of new reactors is completed, bomb-grade plutonium for a new generation of weapons…

But the billions in new proposed American aid, officials acknowledge, could free other money for Pakistan’s nuclear infrastructure, at a time when Pakistani officials have expressed concern that their nuclear program is facing a budget crunch for the first time, worsened by the global economic downturn. The program employs tens of thousands of Pakistanis, including about 2,000 believed to possess “critical knowledge” about how to produce a weapon.