In a video released by U.S. Naval Forces Europe, one of the Russian planes is shown flying an estimated 500 meters (1,640 feet) off the side of the ship at an altitude of 600 feet.

The Navy said it would not have released the video if it didn’t want to publicly counter the Russian reports.

The incident comes as Defense Secretary Ash Carter warned about the danger of a summer offensive by pro-Russian separatists, who have seized Crimea from Ukraine.

“We are looking at Russian activities, at the activities of separatists. It’s a serious possibility and a serious danger,” Carter told the BBC in an interview published Monday.