WASHINGTON >> The Obama administration on Friday accused a Chinese fighter jet of conducting a "dangerous intercept" of a U.S. Navy surveillance and reconnaissance aircraft off the coast of China in international airspace — the fourth such incident since March.

The Pentagon press secretary, Rear Adm. John Kirby, said Washington protested to the Chinese military through diplomatic channels, calling the fighter pilot’s actions "unsafe and unprofessional." And U.S. officials said this is at least the second formal complaint American diplomats have filed with the Chinese over these military actions in recent months.

At a news briefing at Martha’s Vineyard, Massachusetts, where President Barack Obama is vacationing, Ben Rhodes, deputy national security adviser for strategic communications, called the intercept "a deeply concerning provocation" and suggested it could set back efforts to improve relations.

"What we’ve encouraged is constructive military-to-military ties with China, and this kind of action clearly violates the spirit of that engagement," Rhodes told reporters.

U.S. officials said it appears that the same Chinese military unit out of a base on Hainan Island was responsible for similar aggressive "close intercepts" in March, April and May. The officials refused to provide any details of the previous incidents but said the U.S. filed a similar formal complaint with the Chinese in May.

The officials spoke on condition of anonymity because they were not authorized to discuss the previous incidents publicly.

Kirby said the Aug. 19 maneuvering by the Chinese jet posed a risk to the safety of the U.S. air crew, was "inconsistent with customary international law," and complicates efforts to improve military-to-military relations, which are often strained.

Kirby said the Chinese jet made several close passes by the Navy P-8 Poseidon plane, coming within 30 feet of it at one point. He said the Chinese jet did a "barrel roll" maneuver over the top of the Poseidon at one point and also passed across the nose of the Navy plane, exposing the belly of the fighter in a way apparently designed to show that it was armed.

Kirby said it happened about 135 miles east of China’s Hainan Island. In 2001 a Chinese jet collided with a U.S. Navy surveillance aircraft off Hainan Island, killing the Chinese pilot and forcing the Navy plane to make an emergency landing on the island. Washington severed military relations with China after that episode.

The Navy’s P-8 Poseidon aircraft are designed for long-range missions including intelligence collection and reconnaissance.