Chinese jets come within several hundred feet of US plane over South China Sea

— -- Two Chinese J-10 fighter jets came within several hundred feet of a U.S. Navy P-3 Orion over the South China Sea on Thursday local time, U.S. officials said.

The fighters flew 200 yards in front of the P-3 maritime surveillance aircraft with an altitude separation of 100 feet, U.S. officials said.

A defense official described the Chinese intercept as "unprofessional."

According to a U.S. official, the Chinese jets were weaving ahead of the American plane, an action that concerned the U.S. pilot.

The activity occurred 150 miles southeast of Hainan Island in the northern part of the South China Sea.

This encounter appears to have occurred the same day that the U.S. Navy destroyer USS Dewey sailed within 12 miles of Mischief Reef in the South China Sea, conducting a Freedom of Navigation Operation by the artificial island claimed by China.

The U.S. military conducts Freedom of Navigation Operations worldwide to challenge what the U.S. sees as excessive maritime claims and to ensure free and open waterways under international law.

The Dewey's trip was the first such operation near a South China Sea island claimed by China since October and the first under the Trump administration.

Mischief Reef is one of the manmade islands that China has built up in the Spratly Islands chain and turned into airstrips and facilities that could be used by China's military.

Last week, the Chinese conducted a barrel roll over a U.S. Air Force WC-135 radiation “sniffer” aircraft, known as Constant Phoenix, flying in international airspace in the Yellow Sea west of the Korean peninsula.

That incident was also characterized as "unprofessional," a U.S. official said.

ABC News' Elizabeth McLaughlin contributed to this report.