Fallout - *cough*Fallout 4*cough*

Thing is, you wouldn't be able to kill communists with Liberty Prime. While it may seem big and powerful, it's useless tactically speaking. The amount of time, energy and resources required just to transport it to a field of war where it would be useful would vastly outweigh the potential rewards. The whole point of liberty prime is how it was made by Leaders who cared more about big, flashy guns and showing the world how big their dicks are than practicality or efficiency.

And keep in mind that the entire world, America included, was going through an energy crisis pre-war. That's the whole reason China invaded Alaska. With that perspective, Liberty Prime is even more wasteful and impractical.

I'd say that eating three meals a day let's you outlast them pretty quick.