Afaik there are three buttons, each one held by a senior member of the US Goverment, & two of the three buttons must be pressed for the launch of nuclear weapons to happen. Idk what are the UK, French, Russian, Chinese, & Israeli (?) protocols for a nuclear launch. Given the stated intention of the IRGC to destroy Israel it is unlikely that they will build in any restrictions or safeguards to prevent use of their nukes should their supreme leader decide to launch. The operating assumption of MAD (Mutually Assured Destruction) is that nobody wants to die & will therefore be most reluctant to make the first launch which will doubtlessly trigger retaliationry strikes that will assuredly destroy the initiating country too. The entire basis of MAD falls away & ceases to play any role when at least one party with nuclear bombs does not value life as Westerners do. Islamicsts from various organisations have repeatedly stated that they love death more than Westerners love life hence the preponderence of suicide bombers in their ranks who have detonated explosives which eliminate themselves