The discovery was made after RAF specialists analyzed a four-second signal transmitted from one of the Tupolev Tu-160 bombers, known by Nato as “Blackjacks”, in the days following Thursday’s incursion.
Analysts at RAF Boulmer, Britain’s Control and Reporting Centre, confirmed that the Russian bombers had begun the sequence to arm nuclear weapons while carrying out the incursion.
It is not the first time they have done this and comparison with a similar signal transmitted by a TU-95 “Bear” bomber revealed Russian air crew had begun the countdown during an incursion last year, as well.
The Sunday Express revealed that the bomber involved in the February 2014 incident had been carrying a submarine-busting nuclear depth charge designed to attack Britain’s Trident-carrying Vanguard submarines.
“All I can say is that we now know it related to the first stage of arming a nuclear device,” said a senior RAF source last night.