I am afraid this is hyperbole - the US military's post WWII record of destroying the enemy is second to none - entire countries have been shattered by force of US arms. There was never a situation where the US Army wasn't going to win a fight, at any scale.

Why US strategic aims were not fulfilled have more to do with the nature of those aims and erroneous axioms that drive it. People do not like being conquered and will resist occupation until the occupiers leave.