India and China have reached an agreement on patrolling their shared Himalayan border, according to the two governments, potentially easing the icy hostility between the Asian giants after a deadly skirmish between their troops four years ago.

India’s foreign secretary, Vikram Misri, said during a news conference on Monday that the border agreement had come after weeks of intense talks between diplomatic and military negotiators from both sides. The agreement, Mr. Misri said, was designed to lead to “disengagement and a resolution of the issues that had arisen in these areas in 2020.”

Asked about reports of a border patrol deal, a Chinese foreign ministry spokesman, Lin Jian, said on Tuesday that China and India had been in “close communication.”

“Now both sides have arrived at a resolution on the relevant matter, which China views favorably,” Mr. Lin said. “Going forward, the Chinese side and Indian sides will implement those resolutions.”

India made its announcement a day before the opening of a summit of the BRICS nations, a group of emerging-market countries that includes India and China. Indian officials were silent about whether Prime Minister Narendra Modi would hold a bilateral meeting with the Chinese leader, Xi Jinping, at the summit, which is being held in Kazan, a city in southwest Russia.

But the timing of the announcement indicated that Mr. Modi might address the political and economic implications of a military disengagement along the border. Any thaw between India and China could have global implications as the United States courts New Delhi to act as a counterweight to Beijing.