Even though Ukraine isn't a NATO member, it's in NATO's interest to aid non-members. Article 5 is brittle - the smallest invasion of a member nation means calli

Even though Ukraine isn't a NATO member, it's in NATO's interest to aid non-members. Article 5 is brittle - the smallest invasion of a member nation means calling a bluff on nuclear war. Ukraine stands between Russia and Article 5 - literally, in the case of Romania, Poland and Hungary. by making it extremely expensive for Russia to take Ukraine, it kept Russia from pressing its luck. So yes, we have no formal obligation to help Ukraine, but they're our ally - informally - because our interests align for strategic reasons.