The lesson is clear. You cannot delegate your defense to others if they are in competition with you. I don't understand why my comment got so many downvotes. I would have appreciated a discussion on the topic instead.
Europe (excluding Russia) has the second most powerful military in the world on most accounts, with proper technological replacements for everything sold by the Nato ally on the other side of the Atlantic. (Much thanks to Charles De Gaulle who knew the Americans could not be trusted).
But a war with the Moscow State going on in Europe is a big thing. Which of course makes Europe weak in the west, and can be taken advantage of.
I think the lesson learned here is that Europe (and Canada) needs to close ranks and unite. Which may not be a preferable outcome for USA. And before T with a functioning Nato command, there were simply no reason to do that.