It seems fairly likely that Putin's plan to invade Ukraine is because he perceives the US as weak, especially following the Afghanistan withdrawal.
So one part of what he is doing is to demonstrate US weakness.
But if Biden can scare Putin into a reversal, I'll stand corrected about Afghanistan. That Biden got away with it without a huge cost, from a US perspective.
It's already a known fact that continental Europe is weak on defence. It's tragic that it doesn't contribute more.