Two weeks ago, two British Tornado F3 fighter aircraft were scrambled from the Royal Air Force base Leuchars, the United Kingdom’s most northerly air defense station, to pursue two Russian Tupolev 160 bombers which were approximately one hundred nautical miles to the west of Stornaway on the northwest coast of Scotland.

More than twenty of such incident have occured over the last year, the Ministry of Defense revealed on Wednesday. In scenes that harken back to Cold War era saber rattling, Moscow has been issuing planes to probe British air defenses in what largely appear to be a shows of strength.

In the last incursion, the Tornadoes shadowed the Russian aircraft for four hours as they progressed south before the Blackjacks, as the Tupolevs are known in NATO jargon, turned north, short of the Northern Irish coast, exiting British airspace.

An anonymous source has said that the Russian pilots refuse to communicate with the British authorities during their sorties, further shrouding the exact purpose of their flights in mystery.

The Tupolev 160 supersonic heavy bomber is the largest variable-wing and largest jet-powered combat aircraft ever built. It entered service in 1987 and was the last strategic bomber designed by the Soviet Union. At least sixteen remain in service with the Russian Air Force today.