BEIJING -- A Chinese early warning aircraft and U.S. Navy patrol plane had an “unsafe” encounter over the South China Sea this week, the U.S. Pacific Command said Friday, in the first such incident known to have taken place under President Donald Trump’s administration.

The interaction between a Chinese KJ-200 and a U.S. Navy P-3C plane took place on Wednesday in international airspace, Pacific Command spokesman Robert Shuford said. He did not say what was unsafe about the encounter, although the term usually implies planes flying too close to one another.

Shuford says the U.S. plane was on a routine mission and operating according to international law. The Department of Defense and the Pacific Command “are always concerned about unsafe interactions with Chinese military forces,” he said.

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The Chinese Defense Ministry did not immediately respond to a faxed request for comment.

However, the website of the Communist Party newspaper Global Times quoted an unidentified ministry official as saying that the Chinese pilot had responded in a “legal and professional manner.”

“We hope the U.S. side will focus on the relationship between the two countries and two militaries in their entirety, adopt concrete measures and eliminate the root causes of accidental incidents between the two countries on sea and in the air,” the unidentified official was quoted as saying.

Such incidents have occurred occasionally over and within the South China Sea, which China claims virtually in its entirety. Although China says it respects freedom of navigation in the strategically vital area, it objects to U.S. military activities, especially the collection of signals intelligence by U.S. craft operating near the coast of its southern island province of Hainan, home to several military installations.

In recent years, the sides have signed a pair of agreements aimed at preventing such encounters from sparking an international crisis, as happened in April 2001 when a Chinese jet fighter collided with a U.S. surveillance plane over the South China Sea, leading to the death of the Chinese pilot and China’s detention of the 24 U.S. crew members for 10 days.