There is a considerable history of the US wanting Greenland:
https://en.wikipedia.org/wiki/Proposed_United_States_acquisi...
> The problem is who do we ally with that we can trust now.
"We have no eternal allies, and we have no perpetual enemies. Our interests are eternal and perpetual, and those interests it is our duty to follow." ― Lord Palmerston
There are lots of possible allies, but no one single ally to depend on. India to counter balance China, Canada to have an ally in North America, etc.
> it's worrying that the EU doesn't have a mechanism to expel countries.
Or it can become a federal state.
Well yes the US has wanted it but never actually threatened to invade it before.
And no I don't think it's a good idea for Europe to become a federated state. The US' current situation shows how bad that could turn if the wrong person is elected.
At least we have the national governments here as a safeguard and we can also leave the EU if needed.
And yeah I didn't name India as a possible partner because they're too close with Russia. The EU is trying to make some deals with them but it's a bad idea while Modi and the BJP in general is in power in my opinion. They're similarly bad to minorites as the Chinese.