Russia has detected 21 foreign reconnaissance aircraft close to its air space in the course of the past week, an infographic of the Russian Armed Forces' official newspaper Krasnaya Zvezda showed on Friday.

According to the material, Russian jets have been scrambled four times to intercept the foreign planes and prevent them from crossing into the Russian airspace.

The had been no trespasses, the outlet read.

Last week, the Russian Ministry of Defence has confirmed that a USAF B-52H was spotted flying over neutral waters in the Baltic Sea, adding that the plane's sudden u-turn manoeuvre was made after it was picked up by Russian air defences.