The US has the best and strongest air and naval forces in the world. But aside from the Corps of Engineers and special forces, the US Army is terrible. I would go so far as to call the army a liability at this point. Anytime we engage in a war where our air and naval forces are not a factor, we always lose. The army has a WWII organization still and we have been fighting and losing guerilla wars for decades.
Marines are innovative, disciplined, and possess this thing called leadership that is lacking everywhere in American business and government. The US Navy has always been the lynchpin to our success in war and imperial expansion. The air force, though corrupt, is brilliant. What it may lack in fiscal prudence, it makes up for with shear competence.