Well, the president can sure as hell not send troops when the feckless NATO bureaucrats inevitably write checks that their countries cannot cash. It is essentially the same thing as "Yes we are married but I am never home because I am sleeping with someone else and you can pay your own bills."
If NATO doesn't like it they can piss off.
The defense obligation is not that much of GDP.
Maybe Europe isn’t interested in having their civilization anymore.
Their leaders certainly seem to act this way, letting barbarians in to kill their people.