A Russian fighter flew within 50 feet of a U.S. reconnaissance plane flying over the Baltic Sea, barrel-rolling over the top of American RC-135 in a dangerous maneuver that put the U.S. aircrew at risk, U.S. European Command said.

"This unsafe and unprofessional air intercept has the potential to cause serious harm and injury to all aircrews involved," said Navy Capt. Danny Hernandez, EUCOM spokesman. "More importantly, the unsafe and unprofessional actions of a single pilot have the potential to unnecessarily escalate tensions between countries."

The incident, which took place Thursday in international airspace over the Baltic Sea, is the latest in a string of incidents that have brought Russian and U.S. forces into close contact. On Monday and Tuesday, Russian fighter jets buzzed the Navy destroyer USS Donald Cook in the Black Sea, prompting formal protests by the U.S.

During Thursday’s incident, the U.S. RC-135 was flying a routine route when it was intercepted by a Russian SU-27, EUCOM said.

"The Su-27 performed erratic and aggressive maneuvers," Hernandez said. "More specifically, the SU-27 closed within 50 feet of the wing-tip of the RC-135 and conducted a barrel roll starting from the left side of the aircraft, going over the top of the aircraft and ended up to the right of the aircraft."

During the past year, there have been several close encounters between Russian and U.S. forces by sea and in the air. However, the recent Russian maneuvers appear to be getting more provocative, with a Pentagon official saying last week the moves were "more aggressive than anything we’ve seen in some time."

The incidents come as the U.S. pushes forward with plans to expand its presence along NATO’s eastern flank, which has been an area of increased focus in the wake of Russia’s 2014 intervention in Ukraine. Next year, the U.S. Army also plans to deploy a rotational heavy brigade to Europe, along with tanks and other armor, that will be positioned in and around the Baltics. Russia has criticized those plans and warned of countermeasures.

Russia’s defense ministry on Saturday disputed the U.S. account of Thursday’s incident, telling CNN that the Russian fighter responded to an unidentified aircraft flying toward the Russian border and that the SU-27 "performed strictly in accordance with the international regulations on the use of airspace."

EUCOM said the American aircraft was flying in international airspace and at no time was headed for, or crossed into, Russian territory.

"There have been repeated incidents over the last year where Russian military aircraft have come close enough to other air and sea traffic to raise serious safety concerns, and we are very concerned with any such behavior," Hernandez said.

vandiver.john@stripes.com