That's really not cool. It's basically says to Europe "your on your own with Russia". And to Russia "Go ahead, we won't fight you." Which means Putin will go further than invading Ukrainian. Which mean the EU has to go to war to call his Bluff. You could be looking at WWIII. The US will get sucked in regardless of how isolationist it wants to be. Just like WWI and WWII. So not cool to go pushing over dominoes of the post WWII world order. Especially dumb as the US has benefited a lot from said order.