Such protocols did not prevent the two countries from engaging in their deadliest violence in more than 50 years in June, when Chinese soldiers armed with clubs studded with nails and metal rods clashed with Indian troops in a remote area of the western Himalayas.
Twenty Indian soldiers were killed. The number of Chinese casualties remains unknown.
Both countries moved thousands of troops as well as tanks, artillery and fighter jets to areas close to the disputed and unmarked border, which is known as the Line of Actual Control.
Experts say that starting in May, China intruded into areas claimed by India at several points along the frontier and might now control as much as 400 square miles of territory that India considers its own. Months of talks have failed to reduce tensions.
Last week, President Trump said that the situation between India and China had been “very nasty” and that the United States stood “ready to help.”
Col. Zhang Shuili, spokesman for the People’s Liberation Army (PLA) Western Theater Command, said in a statement early Tuesday that Indian troops had “blatantly fired upon Chinese border patrols with threatening shots” near the southern bank of Pangong Tso, a lake in the Ladakh area. In response, Chinese troops took unspecified “countermeasures,” he said.
“These are serious military provocations of a terrible nature,” Zhang said. China demanded that India restrain its troops and punish the soldiers who fired their weapons.
India denied that its troops had used firearms. Its Defense Ministry released a statement saying that PLA soldiers were approaching a forward position on the border and “fired a few rounds in the air in an attempt to intimidate” Indian troops.
An Indian official with knowledge of the incident, who spoke on the condition of anonymity because he was not authorized to discuss the matter, said that Chinese soldiers were making a repeat attempt to cross the Line of Actual Control at a particular location. When Indian troops told them to go back, the official said, the Chinese soldiers “became aggressive and fired shots” in the air.
Indian troops also fired warning shots, according to two army officers stationed in the region who spoke on the condition of anonymity because they were not authorized to speak to the press.
A fresh spike in tensions occurred last week. Indian soldiers went up to the border line claimed by India near Pangong Tso, which straddles the frontier. There they took control of “dominating heights that will give us an advantage over the long term,” the Indian official said.
China responded angrily, saying that India had “illegally crossed the LAC, made provocations, changed the status quo in the border areas and violated bilateral agreements.”
China’s current behavior is driven, at least in part, “by a tougher stance on sovereignty issues” under President Xi Jinping, said Bonnie Glaser, director of the China Power Project at the Center for Strategic and International Studies.
Xi has said that the country will never give up an inch of territory, and Beijing has become more strident in asserting such claims in recent years, Glaser said, whether in the South China Sea or the Taiwan Strait.
Apart from fighting a war in 1962, India and China have largely resolved flare-ups along their 2,200-mile border through dialogue. In 1975, four Indian soldiers were killed in the eastern Himalayas, the last time both countries acknowledged the use of firearms at the frontier.
India and China later brokered successive agreements that laid out how their troops should react when their patrols encountered each other in areas they both claim, including unfurling banners and shunning the use of firearms. While the border remained unsettled, any tension was focused on a few key disputed areas.
All of those understandings have now vanished. “You have a complete breakdown of agreements and protocols, and you have deep suspicions on both sides,” said D.S. Hooda, a retired general who previously commanded the Indian army’s forces in Kashmir and Ladakh.
The current buildup at the border is inherently dangerous, experts said. The use of firearms is “an example of unintended escalation that can pick up momentum,” said Ajai Shukla, an Indian defense analyst and former army officer who has written extensively about the standoff. “All it takes is one red-
blooded guy on the other side to fire back, and before you know what’s what, you’re in a good old-fashioned firefight.”
Christopher Clary, a political scientist at the State University of New York at Albany and a former Pentagon official, said the risk of violence rises when troops are in close contact and especially when “they are trying to deny one another access to sites of tactical or operational significance.”
India and China both have “plenty of firepower in the region, so things could get quite ugly quite quickly if the restriction on firearms becomes inoperative,” he said.
With the standoff showing no signs of ending, both India and China are preparing to maintain their deployments on the barren Himalayan heights throughout a long, harsh winter. Temperatures plunge to minus-22 degrees Fahrenheit, said Hooda, and the two main roads into Ladakh are cut off, forcing India to stockpile supplies well in advance.
The last war between India and China, in 1962, unfolded in October and November. After that point, the weather makes large-scale operations practically impossible, experts said. It is “nature’s way of calling a truce,” said Bharat Karnad, a security expert in Delhi.
Shih reported from Taipei, Taiwan. Shams Irfan in Srinagar, India, contributed to this report.