States hold war materiel and personnel on military bases, these weapons have long supply chains and generally cannot be hidden. Once you've blown these things up, then the state cannot make war any longer.
With aircraft, missiles, satellites, AWACS, advanced intelligence capabilities, the expected speed of conflicts has gone from days to hours in the last few decades. The US enjoys complete dominance over the rest of the world's militaries. There is no state, no imaginable alliance of states that could withstand a full-scale US military attack. We'd destroy their air forces, naval forces, and any ground forces they could muster within hours.
So long as we refuse to fight an unconventional war, then our troops could just go home. It's because our leaders get cocky and idealistic that we get dragged into ongoing guerrilla conflicts.
How do you know that? The only conventional war I know of that was decided in hours was the Six-day war and that was because Israel inflicted a surprise attack on Egypt. Not saying you are wrong, just curious why you think so since the US hasn't been facing an equal adversary in war since WWII.