Though India has been a nuclear power since 1974, its rival, Pakistan, first tested nuclear weapons in 1998.
Pakistan's military said in a statement that it had successfully test-fired a new version of its short-range, nuclear-capable missile today, the Associated Press reported.
Supporters said that rather than fueling arms development, the agreement will promote economic growth in the U.S. and India by easing political tensions and encouraging trade.
"India is a state that should be at the very center of our foreign policy and our attention," Rep. Tom Lantos (D-San Mateo) said in House debate Friday.
Sanjay Puri, chairman of the U.S.-India Political Action Committee, said some estimates had placed the potential economic value of the deal at $30 billion in the United States and India alone, and that it could add 10,000 to 15,000 jobs in the U.S.
Alternatively, the failure of the deal would have "serious repercussions in terms of the political and economic relationship," he said.
The issue of Iran's nuclear ambitions delayed the measure's consideration until the last days of the 109th Congress. Legislators wanted assurances that India would cooperate with U.S. efforts to punish Iran, with sanctions if necessary, for its nuclear program.
But Bush administration officials feared such provisions would alienate India and scuttle the deal.
Ultimately, the two sides agreed on a compromise under which the president would submit reports on India's actions regarding Iran.
Under the agreement passed by Congress, India would be allowed to expand its nuclear weapons arsenal, but for the first time it would allow international inspections of its civilian reactors. However, inspectors would have access only to 14 of 22 reactors. The others, at military installations, would remain off-limits.
At the heart of the debate was the impact the deal would have on the nonproliferation treaty, a cornerstone of U.S. nuclear weapons policy since 1970. The treaty, aimed at preventing nonnuclear nations from acquiring atomic arms, has been signed by more than 180 countries.
Critics of the U.S.-India deal said it would undermine the treaty, encourage violations and lead to the spread of nuclear weapons.
During the debate Friday, Rep. Edward J. Markey (D-Mass.), who had been among the most vocal opponents, said the U.S. was asking the United Nations to pressure Iran, a signatory to the treaty, "not to use civilian nuclear materials in order to create a military nuclear weapon."
