Updated

Two Chinese aircraft conducted an unprofessional intercept of a U.S. Navy surveillance aircraft over the South China Sea, the Pentagon said Friday, marking the second time in about a week that the U.S. has complained about unsafe Chinese operations in the region.

A defense official said one of the Chinese J-10 fighter jets flew about 200 yards in front of the U.S. P-3 aircraft and about 100 feet above it, doing slow turns. The second Chinese fighter remained about 750 yards off the P-3's right wing. The official wasn't authorized to discuss the issue publicly and spoke on condition of anonymity.

Navy Cdr. Gary Ross said the Navy P-3 Orion was operating in international airspace. He said the U.S. is reviewing the incident and will convey concerns to the Chinese.

Last week, U.S. defense officials said two Chinese SU-30 jets conducted an unprofessional intercept of an American radiation-sniffing surveillance plane in the East China Sea.

Pacific Air Forces spokeswoman Lt. Col. Lori Hodge said at the time that the Chinese aircraft approached a WC-135 Constant Phoenix aircraft — a modified Boeing C-135 — conducting a routine mission in international airspace in accordance with international law.

The WC-135 crew characterized the intercept as unprofessional "due to the maneuvers by the Chinese pilot, as well as the speeds and proximity of both aircraft," Hodge said.

China denied U.S. accusations about last week's intercept, saying its aircraft conducted a safe and professional operation.

Defense Ministry spokesman Wu Qian said the American plane was conducting surveillance over the Yellow Sea — the northern part of the East China Sea — and that the Chinese jets moved to identify and verify the plane "in accordance with laws and regulations."

In a separate incident this week, China protested a U.S. Navy patrol that sent a guided missile destroyer near a group of man-made islands in the South China Sea, in the first American challenge to Beijing's claims to the waters since President Donald Trump took office.

China's Defense Ministry told reporters that it had sought an explanation with U.S. officials over the Thursday incident, which Beijing said involved the USS Dewey and took place around Mischief Reef, one of a chain of artificial islands China has built and fortified to assert its claims over the strategic waterway.