Ask Lemmygrad

It's designed for a mass engagement against another superpower. Most of their arsenal is dedicated to countering the best weapons of a country like Russia or China, which they've lagged behind in due to the parasitic defense contractors. You can't achieve a counterinsurgency campaign with bombs though. Killing one civilian radicalises twenty. As an occupation force the US doesn't have enough public goodwill to fill the role of UN peacekeepers and they don't invest enough in reconstruction/provision efforts to build that goodwill.