It is stuff like this that makes Donald Trump sound nuts: Trump says he’d disregard NATO treaty, urge Russian attacks on U.S. allies [1].
It is fine to expect our NATO allies to do more to provide for their own defense, but you cannot threaten to abandon your treaty obligations and not defend them if they are attacked. It undermines the strength of NATO, which is critical to the defense of Europe and the U.S., and emboldens our enemies, including Russia and China.