I know what's wrong with liberals!!
I have figured it out, folks. Gather 'round.
You see, they just aren't able to tell the difference between evil countries like Hitler's Germany or Stalin's USSR using military force to conquer and enslave other nations, and the USA using military force to liberate and democratize other nations. It's sort of like being colorblind, only instead of not being able to see different colors they can't discern different shades of morality.
We can only hope that one day medical science will develop a cure for morality blindness.