Russia’s defense ministry said a Russian Su-35 fighter jet was scrambled over the Baltic Sea to intercept two US B-52H strategic bombers flying towards the Russian border, state news agency TASS reported on Monday.

“Radars of the Western Military District Air Defense force on duty detected two airborne targets over the Baltic Sea, flying towards the state border of the Russian Federation,” TASS cited the ministry as saying.

The Russian ministry said the targets were “two US Air Force B-52H strategic bombers”.

The Su-35 jet was scrambled to identify the planes and prevent a border violation, according to the defense ministry which added, “after the foreign military planes moved away from the state border of the Russian Federation, the Russian plane returned to its home base.”

The ministry stressed that the planes did not violate Russia’s state border and that the Su-35 jet’s flight was “in strict compliance with international air law.

This incident follows the March 14 crash of a US military surveillance drone (MQ-9 Reaper) into the Black Sea, after an encounter with Russian Su-27 fighter jets in international airspace near territory Russia claims to have annexed from Ukraine. This was the first such incident between Washington and Moscow since the latter launched its invasion of Ukraine in February 2022.

The US and Russian offered different versions of events diverging over the cause of the drone’s crash. The US maintained that a Russian Su-27 jet clipped the propeller of the drone which led to the crash; while Russia denies any physical contact between its jets and the drone, and says, “the device went out of control as a result of sharp maneuvering,” then crashed.

Moscow warned Washington against violating the Russian border and said it would respond “proportionately” to any future “provocations” by the US.