Russia scrambled an Su-27 fighter on Tuesday to intercept a US B-52 bomber over the Baltic Sea, the Russian defence ministry said.
The B-52 was in international airspace but close to the Russian border, and was escorted away, the ministry said.
The Su-27 then returned to its Baltic Fleet airbase.
A similar incident happened on 9 May over the Black Sea, involving a US P-8A Poseidon surveillance plane and a Russian Su-30 fighter.
Separately on Tuesday, Russian media reported that a Russian fighter jet had been scrambled to intercept a Norwegian patrol plane over the Barents Sea.
Russia and Nato have boosted their military forces in the Baltic region amid an escalation of tensions over Ukraine.
Russia has based nuclear-capable Iskander missiles at its Kaliningrad exclave in the Baltic, and Nato says Russian air patrols have increased in the region.
Russia has condemned Nato’s military deployments near its Baltic borders, accusing the alliance of aggression.
Russia’s annexation of Crimea in 2014 and the conflict in eastern Ukraine led to the worst political chill in Europe since the Cold War.