"On the evening of 6 July, Russian airspace control means over the neutral waters of the Black Sea detected an air target approaching the state border of the Russian Federation", the ministry said in a statement.
Two Su-30 fighters took off to identify the aircraft and prevent it from entering Russian airspace.
"The crews of Russian fighters identified the air target as a Boeing P-8 Poseidon and escorted it over the Black Sea. The flight of Russian aircraft was carried out in strict accordance with international rules for the use of airspace", the statement said.
The Russian state border was not violated, the ministry added.