I thought about that, but we do not have the military ability to do so. Guam is out of range of Alaska and California AMBs, and the ship based ones work about 50% of the time.
Oh, sheet!
Use the ship based ones. If they don’t work then we need to know that.
Then launch two ship-based missiles.
In the industry it’s called “shoot-look-shoot” or “salvo”.
So you fire twice. Problem solved.