Pay 2% of GDP on Defense first.
Also if the EU wants to stand up to the US and they refuse to pay their 2% fee the US should make sure their are some consequences for this .
What fee are you talking about? Good Lord, there is no "NATO FEE", it simply does not exist.
Each country pays into its own defence budget, and the 2% is a "NATO recommendation", not a fee.
The EU military budget is around $230 Billion, so yeah, I think it is enough, considering that it is on par with China (a country with 3x the population), and 4 times the amount Russia invests.
So yeah, unlike what you think, no one is invading Europe if you pull out, seeing as it is the 2nd/3rd biggest spender after the US.
It looks good on the paper, but the EU militaries aren't integrated, or even properly coordinated to act as one force. It's basically like the U.S. without its army, relying on state militias (with huge differences in budget, capabilities and equipment) jumping together in time of crisis.