Our country has disproved its own illusory military superiority when it comes to Iraq and Afghanistan. We can get in and blow things up; but, we can't secure the aftermath.
We are unwilling to merely blow things up. We assert our preference for political end games that tip the balance of power in favor of a democracy. But, we can't MAKE it happen.
Taking on Korea or Iran would not get us what we desire. What America desires is customers!
We do fine with China now because they are customers and we are theirs. We both have something to gain and lose.
But, with Korea and Iran we stand to lose without gaining.
It is pointless to succumb to the illusion that military power can do anything other than postpone the outworking of imbalance in the human condition.
We carry a big stick, but, we've wielded it in the wrong place at the wrong time.
The most successful military power on earth was the Roman Empire that lasted well over a thousand years. They never struck first as a military power and always waited for invitation of pretext. When they conquered, they let locals rule under supervision. When anyone challenged their Pax Romana the justice was swift and complete. Where Rome faltered was in trying to defeat peoples who could hit and run at will. Many a legion was lost when the enemies they faced refused to line up and march into their spear points.
The ultimate defeat of the power of Rome was immigration. Enough barbarians were hired as mercenaries to fight in the army that there was no espirit de core when push came to shove. Barbarians don't fight barbarians with as much conviction as Romans.