The point is regarding the deterrent concept, for it to work, you have to be prepared to actually use it.
Nobody in their right mind would ever consider detonating a nuclear bomb, as amongst other things if that scenario happened, then it has failed to deter anybody or anything. After all, the nine nuclear weapon states (USA, UK, France, Russia Federation, China (all permanent members of the United Nations Security Council, and also signatories to the NPT (Non Proliferation Treaty) which states in its articles that "... to disarm in good faith"), India, Pakistan, DPRK/North Korea, and Israel (still to actually fess up to possessing them) failed to stop the Iran-Iraq conflict (Saddam Huessain was best buddies with Regan and Thatcher, and funded and trained him), the former Soviet Union occupation of Afghanistan, the assassination of Salvadore Allende by the CIA on 9/11 1973, the Israeli Government from invading and occupying territory and attacking the aid ship Mavi Marmara using white phosphor (banned in international law) in 2010, the London attacks in 2005, Saudi Arabia's present conflict in Yemen (caused by the UK selling arms to the Saudi Government), the Troubles in Northern Ireland, swine flu, Covid 19, and many others etc.