President Obama met with Prime Minister Narendra Modi of India on Tuesday, moving closer toward finalizing the Paris agreement to limit greenhouse gases.  WASHINGTON — After decades of mistrust and fitful reconciliation efforts, India and the United States turned toward cooperation Tuesday, and Donald J. Trump can claim at least some of the credit.  India’s prime minister, Narendra Modi, making his second visit to the White House in two years, announced a crucial step toward ratification of the Paris agreement to limit greenhouse gases, bringing the accord close to full implementation.  The two sides also announced that they intended to complete a deal in which India will buy six nuclear reactors from Westinghouse by June 2017, fulfilling an agreement struck in 2005 by President George W. Bush. The price is still under discussion, but more difficult issues like liability have been resolved.  A defense deal, a technology agreement and American investments in India are also expected to be announced on Tuesday. Mr. Modi has made clear that he intends to set aside decades of standoffishness — rooted in India’s colonial experience — to cement closer ties with Washington, in part because the next American leader may not share President Obama’s enthusiasm for India.  The news media in India has extensively chronicled comments by Mr. Trump that critics have said were racist, his “America First” views and his unorthodox campaign. While Mr. Trump, the presumptive Republican presidential nominee, has said little about India, his vows to tighten immigration policies worry Indian officials.  “Modi wants to get as much as he can out of Obama’s last months in office,” said Ashley J. Tellis, a senior associate at the Carnegie Endowment for International Peace.  For the Americans, the most important part of Mr. Modi’s visit was his announced intention to formally join the Paris climate change agreement by the end of this year. So far, countries representing about 50 percent of global emissions have announced that they will submit legal paperwork to the United Nations documenting their compliance with the deal.  The pact will become binding when at least 55 countries representing 55 percent of global emissions formally join. The inclusion of India, the world’s third-largest emitter after China and the United States, would guarantee that the deal will go into effect before the next American president takes office.  Mr. Trump has vowed to “cancel” the Paris climate agreement if elected, something Mr. Obama is eager to prevent. Once the accord enters into legal force, no nation can legally withdraw for four years.  “If the Paris agreement achieves ratification before Inauguration Day, it would be impossible for the Trump administration to renegotiate or even drop out during the first presidential term,” said Robert N. Stavins, the director of the environmental economics program at Harvard.  Mr. Obama and Mr. Modi also announced a separate agreement to cut the use of hydrofluorocarbons, potent planet-warming chemicals produced by coolants in refrigerators and air-conditioners. India and the United States have been at odds on the details of such a deal, but the agreement announced Tuesday means both governments now expect in October to sign on to an international accord to phase out the chemicals. Phasing out the chemicals could reduce by 25 percent the expected warming of the planet by the end of the century.  “This is the most significant step the international community could take” to reduce climate warming, Brian Deese, a senior adviser to Mr. Obama, said in a call with reporters.  The two sides also announced joint efforts for the United States to invest in India’s renewable energy development, including the creation of a $20 million finance initiative.  Mr. Modi met with Mr. Obama at the White House in the morning, and the two then had a working lunch. The last time Mr. Modi visited, in September 2014, he was invited to dinner but announced that he was observing a religious fast. So Mr. Obama had the awkward task of eating before a guest who sipped only water. This time, Mr. Modi ate.  On Wednesday, Mr. Modi will address both houses of Congress, becoming the fifth Indian prime minister to do so.  The two countries are expected to announce a military logistics deal that would allow their forces to help each other with crucial supplies, and the United States is expected to agree to allow India to receive military technology usually reserved only for its closest allies.  India’s increasing willingness to form military partnerships with the United States is, in part, a result of its deepening worries about China. Recent patrols by Chinese submarines in the Bay of Bengal have unnerved New Delhi, and a 2014 visit to India by the Chinese president, Xi Jinping, did nothing to soothe Indian sensibilities, as Chinese troops made an incursion into border territory that India claims as its own. China’s refusal in the months since to resolve the territorial claims at the heart of the standoff has quietly infuriated Indian officials.  Another reason Washington and New Delhi have grown so close is the increasingly testy relationship between the United States and Pakistan, India’s longtime rival. Although Pakistan is formally an ally of the United States, American officials have made clear that India has displaced Pakistan in American interests and hearts.  “We have much more to do with India today than has to do with Pakistan,” Defense Secretary Ashton B. Carter said in April. “There is important business with respect to Pakistan, but we have much more, a whole global agenda with India, agenda that covers all kinds of issues.”  Economic cooperation was also on the list for Tuesday’s meeting, with Mr. Modi expected to meet with business leaders. India has the world’s fastest-growing large economy, but it is not growing fast enough to provide jobs to even a significant fraction of the one million people entering the work force there every month. Mr. Modi has largely failed to deliver the kind of major economic overhauls he was expected to carry out after his election two years ago.
Pacts on Tuesday included a crucial step to ratify the Paris climate accord and finishing the purchase of nuclear reactors, with a military deal to come.