The key question is whether North Korea does have nuclear weapons that it can readily use against the United States and its regional allies, South Korea and Japan.
Beijing has traditionally retained its nuclear weapons on a no-first-use basis, but it's ready to deploy them more assertively.
One of the world's worst nightmares could in fact be an unexpected opportunity.
The entire concept of nuclear deterrence depends on the assumption that everything will always work perfectly.
Reports of a failed Trident missile launch have all sorts of political and security implications – but they don't necessarily spell catastrophe.
For decades, deterrence has effectively countered the threat of nuclear weapons. Can we achieve similar results against cyber weapons?
With a $1 trillion modernisation programme signed off and atomic scientists deeply worried about the future, American policy on nuclear weapons is pretty much business as usual.
Is Australia's reliance on nuclear defence agreements keeping us on the wrong side of history?
Laugh at Jeremy Corbyn all you like, but he's right: nuclear deterrence isn't a zero-sum game.
Splits over Trident can create stalemate between the UK's forces, but the public needs to debate renewing the deterrent before time runs out.