Germany and other European nations explored possible responses, including invoking NATO’s Article 5, though it was ruled out due to US veto power.
And this is the only reason why Trump didn't pull the US out of NATO.
Because of the veto power, he can effectively block them from taking action against the United States.
NATO is dead.
If other world leaders had half a brain between them, they would be forming a new alliance without the United States as we speak.
They literally can't, the US is a permanent member.