Canada

I was thinking like this a few weeks ago but with more thought I think we are geographically too difficult to invade by force.

It's unfortunately much the opposite; our geography makes us easy to divide and conquer through a combination of the Canadian Shield being difficult to develop on, and the Trans Canada highway being a single point of failure.

https://youtu.be/550EdfxN868

I know the video is about invading the US, but it covers the general strategy the US could easily use to prevent troop movements between the western and eastern parts of Canada.

The rest of the world would also have boots on the ground here to help us out.

The US Navy could easily blockade or destroy the entirety of Europe's combined naval forces in a matter of days. Large-scale troop and equipment transport to bring reinforcement would be extremely unlikely to work, and Europe's militaries know this.

Also I think the vast majority of Americans would just refuse the order to do it.

20 years ago, Ukrainians would never have entertained the idea that Russia would invade and annex them. Many families lived, and continue to live, across both countries. Pernicious propaganda combined with authoritarian rule eventually removed the risk of sufficiently organized opposition.

Will it take 20 years for the US oligarchy to do the same? It's only been two months and we've gone from mutual cooperation to booing each other's anthems in sports games and AI-generated pictures of geese smashing eagles.

Increased trade with China at the US' expense will be the grain of truth buried in Trump's lies about Canada being owned and run by China (it doesn't need to be true, he just needs a fact he can grossly misinterpret, and often, not even that).

I wouldn't underestimate just how thoroughly ignorant and upset many Americans are. A little push in the right direction and the promise of wealth, even if ill-gotten, might be all they need.