NEW DELHI — Growing concern over China’s naval activity in the South China Sea has brought the United States and Asian militaries closer than ever before, and Secretary of State John Kerry on Sunday warned China against encroachments in the region.
Speaking in Mongolia on his way to Beijing for strategic and economic talks this week, Kerry said China would be committing a “provocative and destabilizing act” if it establishes an air defense zone in the South China Sea, the Associated Press reported.
Kerry said the defense zone would raise tensions between China and other Asian countries. He said it also would call into question China’s commitment to resolving disputes over islands and maritime claims diplomatically.
He said the United States doesn’t take sides on competing claims and said no country should move unilaterally to militarize the resource-rich region.
Kerry hailed Mongolia, which is located between Russia and China, as a modern ‘‘oasis of democracy,’’ the AP said.
After lunching with Mongolia’s Harvard-educated president, Elbegdorj Tsakhia, Kerry attended a naadam, an ancient competition with archery, horseback riding, and wrestling, and tried his hand at using a bow.
India is a leading example of Washington’s efforts to broaden military cooperation in Asia.
The Indian military now participates in more drills with the United States than with any other country. The two countries also are close to signing an agreement that would allow refueling and repair of vehicles at each other’s bases, a plan that has been under discussion for more than a decade.
The United States is hoping to shore up its reach in the region with freedom-of-navigation patrols to counter Chinese territorial ambitions in the South China Sea.
India has been critical of some Chinese actions and deployed four warships to the area for exercises last month, but it has generally moved with caution to avoid antagonizing its mighty neighbor and key economic partner.
‘‘Where the South China Sea is concerned, the Indian government understands the risk very clearly of getting needlessly tangled there,’’ said Manoj Joshi, a distinguished fellow at the Observer Research Foundation, a New Delhi-based think tank.
Washington must overcome years of mistrust by India, brought on by the Cold War and over US support of Pakistan.
In a recent speech in New Delhi, the commander of the US Pacific Command, Admiral Harry B. Harris Jr., was nearly poetic when he discussed the growing relationship between India and the United States. ‘‘In the not-too-distant future, American and Indian Navy vessels steaming together will become a common and welcome sight throughout Indo-Asia-Pacific waters,’’ Harris said.
But just a few days later, India’s defense minister, Manohar Parrikar, publicly rebuked him, saying India does not participate in joint patrols.
Prime Minister Narendra Modi of India will arrive in Washington on Monday to meet President Obama and address Congress.
It will be a historic moment for a leader who was once banned from entering the United States.
In 2005, the United States government denied Modi a visa on religious-freedom grounds, after charges that he had not acted to stop Hindu-Muslim rioting in Gujarat, the state where he was chief minister in 2002, that left more than 1,000 dead.
The visit will mark the seventh time Modi and Obama have met since the prime minister came to power in May 2014, a measure of both India’s strategic importance to the United States and what aides say is a genuine rapport between the two men. They will discuss climate change, a clean-energy partnership, and security and defense cooperation.
After India performed a series of nuclear tests in 1998, a near blackout of military cooperation followed. Relations improved after President Bill Clinton visited in 2000, and, in 2008, the countries ratified a landmark agreement on civil nuclear cooperation.
The agreement has yet to bear fruit, but Westinghouse Electric may announce a plan to build six nuclear reactors in the Indian state of Andhra Pradesh in the coming weeks.
‘‘India is really a legacy issue for Obama,’’ said C. Uday Bhaskar, director of the Society for Policy Studies in New Delhi. After the nuclear-cooperation issue was settled in 2008, past estrangement moved to tentative partnership, he said.
The Modi government seems more interested in cooperating than previous governments, analysts say, and Defense Secretary Ashton B. Carter has made India a top priority, with an expansion of defense technology and trade and collaboration on aircraft-carrier design.
The United States is one of India’s top defense suppliers, resulting in $14 billion in defense contracts since 2007.
India is also seeking US support as it attempts to overcome China’s opposition to its entry into the Nuclear Suppliers Group, an organization of 48 countries that aims to limit nuclear proliferation through export controls.
Yet India hedged its bets for years on the key logistics agreement that would enable the United States to refuel and repair vehicles at Indian ports and bases.
The two countries have agreed ‘‘in principle’’ to the deal, but the final draft has not been signed.