We are talking about two B-52 Stratofortress bombers capable of carrying nuclear weapons. They flew over the territory of Bulgaria and the southeastern part of Romania near the borders of Ukraine to the south of the Odessa region. The American side called the flights a "routine operation".
Over Northern Europe, a pair of B-52s of the US Air Force flew over Western Europe. During the 12-hour mission, the sides conducted flights, in particular, over Denmark, Poland and the Baltic.