In other words, every major war we've fought since Korea has been unjustified. It's pretty much what we do.
* Vietnam: Interfered in a civil war between 3rd world countries to stop the spread of communism (we lost)
* 2nd Gulf War: Invaded a sovereign nation to "pre-emptively" remove its leader and eliminate its non-existent WMDs from being used against us (we won)
* Afghanistan: Eliminated the 9/11 perpetrators, then engaged in "nation building" of a 3rd world country filled with religious zealots (we lost)
50 years or so of fighting, and we lost 66% of the time.
At least if we go to war in Ukraine, we get back to our roots of kicking ass, whether it's a war of choice or not.