No, the US is not guilty of War Crimes.

For a country to be guilty of war crimes, they must be a deliberate policy, widley carried out with either orders, or at least acceptence from high up in the chain of command.

Prisoners in one prison being starved for two days, due to an unexpected and unplanned food shortage is not a war crime.

Large groups of prisoners being 'forgot' by the cooks, again and again, is.

There are some US and UK troops guilty of war crimes. They are personally guilty. The countries as a whole are not.