A Chinese military aircraft crossed near the nose of a Navy P-3C Orion anti-submarine and surveillance plane Wednesday, flying within about 1,000 feet in an encounter the Pentagon identified as unsafe, but probably unintentional. The incident occurred late in the morning in international airspace over the South China Sea near Scarborough Shoal, said Navy Capt. Jeff Davis, a Pentagon spokesman. The Chinese plane’s maneuver prompted the Navy aircraft to turn to avoid it.

The incident came one day before President Donald Trump, in a conversation with China’s President Xi Jinping, agreed to honor the one-China policy, after weeks of tension that began when Trump suggested he would only commit to the agreement if China addressed concerns he has about trade and the valuation of China’s currency. The policy rules out independence or U.S. diplomatic recognition for Taiwan, and was first agreed to in 1972 by President Richard Nixon and China’s Mao Zedong.

China, whose expansion in the South China Sea continues to be a friction point with the United States and other nations, had several interactions with U.S. military aircraft in 2014 that raised concerns at the Pentagon. In one case, a Chinese J-11B fighter jet brought the tip of one of its wings within 20 feet of a Navy P-8 Poseidon surveillance plane. But U.S. officials have said those sorts of incidents have dwindled since.

An unnamed Chinese Foreign Ministry official, speaking to the Global Times newspaper, said the incident took place after two Chinese fighters had followed and monitored the U.S. plane “while maintaining a safe distance.” No dangerous action was taken, the Chinese official said.

In December, a Chinese naval ship seized an underwater drone used by the United States to test water conditions in the South China Sea, the Pentagon said.

China returned it within a few days, despite Trump, then the president-elect, tweeted “We should tell China that we don’t want the drone they stole back.- let them keep it!”