"An Su-27 fighter jet as part of the Southern Military District's air defences was scrambled to intercept a target. The crew flew the aircraft at a safe distance from the aerial target and identified it as a US P-8A Poseidon reconnaissance jet, which immediately changed the direction of its flight away from the Russian state border," the ministry said in a statement.
According to Russia's MoD, "the entire flight of the Russian Su-27 was strictly in accordance with international rules for the use of airspace."
A P-8A Poseidon maritime patrol aircraft, alongside a contingent of US Marines and Navy divers, is taking part in Ukraine and NATO's joint Sea Breeze naval drills in the Black Sea. The US Department of Defence has not yet commented on the incident.