I agree with this, but wouldn’t we always have to decide how far we’d stretch the umbrella?
For instance, what if Putin did a Hitler and invaded a NATO member, then another, while threatening nuclear war if we get involved? Are we willing to call his bluff? Even if he’s not bluffing? Would we engage in a nuclear exchange to save Europe? We’ve always said we would.
This is where I think Trump is vs. our policy since NATO’s inception. I think he looks at it as “Russia, you can have your empire and we’ll have ours so long as you don’t invade the USA.” I think that even includes allowing them to overrun Europe. In fairness, they couldn’t overrun the Indiana National Guard with conventional forces, but my scenario includes the use/threat of tactical nukes on the battlefield and ICBM’s against us.