Bringing an end to what was a prior policy of three decades of gradual disarmament, Britain will expand its nuclear arsenal by over 40%, according to a planned announcement by Prime Minister Boris Johnson on Tuesday.

Lifting the cap will mark the biggest shift since the Cold War, which Foreign Secretary Dominic Raab has said is needed as "the ultimate insurance policy" amid a more risky global environment filled with advancing technological and more sophisticated threats from hostile actors. 

Outlining the rationale for such a dramatic ramping up in nuclear arms, Raab explained, "Because over time as the circumstances change and the threats change, we need to maintain a minimum credible level of deterrent."