I could make a fair moral case for invading anywhere bigger than the mini-states like Switzerland.
Are there any countries in the Middle East where there isn't a good justified reason to invade them? I can think of reasonable reasons to invade Israel, Iraq, Iran, Afghanistan, Syria, Saudi Arabia, Yemen and Pakistan. Some of those reasons have actually been used.
Similarly I can think of great justifications for an invasion of China, North Korea, Russia, pretty much all of Africa, the United States (they have a substantial amount of blood on their hands!).
Europe I personally struggle to think of dirt on in the last 50 years, South America I don't know much about. Most of South East Asian nations seem pretty well behaved to me which makes them a global rarity.
The fact that the US invaded somewhere where there were real reasons for concern is nice, but as far as I can tell that would be true of any invasion of any country short of sending the troops into Canada or re-invading Germany. In the Middle East it doesn't really mean much.