US has said that it already had knowledge of Pakistan's plans to build a powerful new reactor to make weapon-grade plutonium.
It has also said that it would seek to discourage both Islamabad and New Delhi from expanding their nuclear weapons programme.
"We have known of these plans for some time and we discourage military use of the facility," said White House spokesman Tony Snow.
"Pakistan is not a party to the non-proliferation treaty, nor is India and, therefore, they do develop their capabilities independently.
"But we continue to discourage the expansion and modernisation of nuclear weapons programmes, both of India and Pakistan," he said.
The US also supported a fissile material cut-off treaty that it had introduced at the UN Conference on Disarmament and continued to impress on all the states that produce fissile material to observe a voluntary production moratorium, as US had done for a very long time, Snow added.
Meanwhile, State Department's deputy spokesman Tom Casey discounted suggestions that the Bush administration was withholding a report showing a connection between India and Iran since the India-US nuclear deal was awaiting Congressional approval.
The semi-annual Iran Non-proliferation Act Compliance Report detailing activities of foreign companies and entities that may have assisted Iran in proliferation activities would be out very shortly, he said, asserting there are no political considerations that are delaying its release to the Hill.