Update at 2:20 p.m. ET
A Chinese fighter jet conducted what is being describing as a "dangerous intercept" of a U.S. Navy P-8 Poseidon in international waters off the island of Hainan in the South China Sea earlier this week, the Pentagon confirms.
Pentagon spokesman Rear Adm. John Kirby said the Chinese fighter's posture was "aggressive and unprofessional," making several passes under and alongside the U.S. Navy maritime patrol aircraft, doing a barrel roll and flying wingtip to wingtip within 20-30 feet of the American plane.
Kirby did not say what type of Chinese fighter was involved.
The incident, he said, took place Tuesday about 135 miles east of Hainan in the South China Sea.
"We expressed our concerns through diplomatic channels," Kirby told reporters at an afternoon briefing that also touched on the situations in Ukraine and Iraq.
Later, Deputy National Security Adviser Ben Rhodes said the Chinese move was a "deeply concerning provocation" and that those concerns had been conveyed to Beijing.
Similar close-quarters maneuvers by a Chinese J-8 interceptor jet resulted in a midair collision with a U.S. Navy EP-3 Orion surveillance aircraft in April 2001, forcing the American plane to land on Hainan island. The crew of 24 was detained there and questioned for more than a week before being released.