Consider the following, modern-day scenario:
- A relative madman is elected as US president
- The US president can irreversibly launch nuclear weapons under 60 minutes without oversight by congress, courts, or state governments for any reason
- The president understands the mutually ensured destruction (MAD) doctrine and its criticisms
- The president learns of a method where he, his immediate family, and select few loyal deputies could start and survive a global nuclear exchange (e.g. US vs Russia/China) and subsequent climate/economic disaster, while neutralizing the rival governments (and a large segment of world's population).
- This method allows for establishing a new, post-nuclear-exchange government, of which, the president and his family/deputies would be the new leaders.
What would be a likely method where a US president+family+deputies could initiate and survive a thermonuclear exchange and govern afterwards?
Edit: Removed question on prevention, and made the question more impersonal.