"US couldn't annex Canada if it wanted to" - Truly, the state of our military is shockingly bad. The US Marines could annex Canada, and I honestly mean that.

I do agree that the US military's perceived preeminence has taken a big blow, but what you're saying is just outrageously false.

I do not think they could. It is not just a matter of seizing something as much as holding it, as everyone has plainly seen in Ukraine, or post-occupation Iraq or Afghanistan.

Neither of those latter countries had a large shared land border with the US and ethnically similar populations that would make it easy to attack unhardened infrastructure.