U.S. B-52H Stratofortress bombers flew Friday over NATO territory close to Ukraine, where Russian forces are waging a full-scale invasion.

The aircraft that flew over Romania, a NATO member bordering Ukraine, were not engaged in combat operations — even if they do serve as a show of force in the face of Russian aggression. The bombers were taking part in close air support and integration mission training, said the U.S. Air Forces in Europe.