I just read through these pages of AdultInTheRoom's cheerleading for Russia. Funny stuff. Yeah, Russia strong like bear, US puny and weak. Lol!
Russia won in WWII, not because they had the greatest military ever, but because they had large numbers of men that they were willing to sacrifice, virtually endless miles of land to fall back on which stretched German supply lines, and allies in the British, US, Canadian, and free French forces that were fighting Germany from the West.
The US military easily defeated the 4th largest army in the World at the time in the 1991 Gulf War (which I served in), probably the most lopsided victory in modern times.
US easily achieved military victories in Afghanistan and Iraq wars and ousted the Taliban and Saddam. The occupation and nation building afterward did not go so well obviously. But still, as unpopular as those wars became our troops still served and fought there very effectively and they all volunteered to enlist and go do that, so I think it is completely absurd for "Adult" to say that Americans don't have the will to fight.