Washington - The United States opened a new chapter of cooperation with India on Wednesday night as Congress gave final approval to a breakthrough agreement permitting civilian nuclear trade between the two countries for the first time in three decades.
The Senate ratified the deal 86 to 13 a week after the House passed it, handing a rare foreign policy victory to President Bush in the twilight of his administration and culminating a three-year debate that raised alarms about a new arms race and nearly toppled the government of India.
The agreement, in the view of its authors, will redefine relations between two countries often at odds during the cold war and build up India as a friendly counterweight to a rising China. But critics complain that it effectively scraps longstanding policies designed to curb the spread of nuclear weapons and that it could encourage nations like Pakistan, Iran and North Korea to accelerate their own programs outside international legal structures.
Under the terms of the deal, the United States will now be able to sell nuclear fuel, technology and reactors to India for peaceful energy use despite the fact that New Delhi tested bombs in 1974 and 1998 and never signed the Nuclear Nonproliferation Treaty. In exchange, India agreed to open up 14 civilian nuclear facilities to international inspection, but would continue to shield eight military reactors from outside scrutiny.
"The national security and economic future of the United States will be enhanced by a strong and enduring partnership with India," Senator Richard G. Lugar of Indiana, the ranking Republican on the Foreign Relations Committee, said in the Senate debate on Wednesday. "With a well-educated overall middle class that is larger than the entire United States population, India can be an anchor of stability in Asia and an engine of economic growth."
Senator Byron Dorgan, Democrat of North Dakota, called the deal a "grievous mistake" that would reward rogue behavior. "We have said to India with this agreement: 'You can misuse American nuclear technology and secretly develop nuclear weapons.' That's what they did. 'You can test these weapons.' That's what they did," Mr. Dorgan said.
He added: "And after testing, 10 years later, all will be forgiven."
Mr. Dorgan and Senator Jeff Bingaman, Democrat of New Mexico, tried to amend the agreement to explicitly require the United States to cut off nuclear trade if India conducted a new nuclear test. The agreement's backers defeated the proposal, arguing that it was unnecessary and that nuclear trade would be halted in such a situation.
Mr. Bush has been pursuing the agreement since 2005 and his advisers have called closer relations between the United States and India a key part of his foreign policy legacy. Prime Minister Manmohan Singh of India, visiting Mr. Bush at the White House last week, endorsed that view. "When history is written," he said, "I think it will be recorded that President George W. Bush made an historic goal in bringing our two democracies closer to each other."
But the nuclear accord has proved even more controversial at home for Mr. Singh than for Mr. Bush. Opposition parties have tried to bring down Mr. Singh's government and the Communist Party dropped out of his governing coalition in protest of the deal, but he survived a confidence vote. Secretary of State Condoleezza Rice heads this week to New Delhi to mark the success of their nuclear negotiations.
For India, the pact signals the end of 34 years of isolation among nuclear powers - what the New Delhi government calls "nuclear apartheid." The United States last month convinced the Nuclear Suppliers Group, a consortium of 45 nations that Washington formed in response to the Indian test in 1974, to lift longstanding restrictions on nuclear trade with India. France and Russia are eager to bid for India's business.
The United States-India Business Council, which promoted the deal, estimates that India may spend as much as $175 billion over the next quarter century expanding its nuclear industry to cope with rising energy demands. Companies like General Electric, Westinghouse and Bechtel will now be able to compete for contracts.
"This is one of those historic, important, tectonic shifts in relations with another country," said Ron Somers, the council's president. "This is a country we need to be partnering with and I would argue will be shaping the destiny of the 21st century." Michael Krepon, co-founder of the Henry L. Stimson Center, a research organization in Washington, called the promise of big dollars and American jobs "pure fantasy" and predicted that the United States would regret further opening the nuclear door.
"There will be a reckoning for this agreement," he said. "You can argue till you're blue in the face that India is a special case. But what happens in one country affects what happens in others."