China legitimately have claim on Taiwan due to unsettled civil war, what claim does US have on Canada or Greenland or Panama Canal? What the War of 1812 is an unsettled matter and they are resuming hostility?
Not here for a normative debate on whether might makes right, but Americans, especially her domestic nationalists, tend to feel rather warm and fuzzy about renewing Uncle Sam's commitment to Manifest Destiny these days.
Many of them genuinely believe, rightly or wrongly, that they or at least the US government would be making the world a better place by further expanding the US and making more people Americans.
This is very much reflected by how recent US administrations sold some rather problematic conflicts to the American public: "We are not invading them, we are bringing them freedom and democracy! Hooyah!"
That's exactly why Trump acts like this. He wants to look tough and aggressive to electrify his base
Mr Trump is just giving his base what they want to see and hear.
Democracy can get rather performative, and gorillas do not possess a monopoly on chest beating.
It's a popular pastime for some modern Western leaders, especially in countries like Britain and France where the head of government and the head of state, respectively, have been feeling particularly politically vulnerable lately.
He needed a big WIN asap and a masterstroke if you ask me
Soon-to-be President Trump is interested in establishing a legacy like any other politician in his position.
However, he doesn't actually need many, if any wins as he won't be running for re-election.
This is probably why he wants to indulge in a Jeffersonian-esque exercise in purchasing Greenland: might not do much for the US in immediate terms, but potentially achievable, and it'll make him the first president to physically expand the United States in three generations.
Panama, Canada, Greenland, Mexico...
What realistically can happen is that the US gets bogged down in Mexico, and Panama
Mr Trump is not going to give Mexicans what many of them have wanted for decades: American citizenship. He might "get tough" with Mexican DTOs, but that can be largely outsourced to Mexico and limited in scope.
Likewise, four years isn't going to be enough time to turn Canada into an American state unless President Trump somehow lucks out on or creates an opportune crisis that'll convince Canadians to eat up the idea of de jure Americanization.
I'm not even going to get started on the inevitable GOP opposition to such a scenario given the long term effects it'll have on the balance of power in Congress . . .
On the other hand, it's plausible that the Trump administration can and will "convince" Denmark to sell Greenland just as Russia sold Alaska when Jefferson was in office.
As for Panama: an US invasion of the country will likely feel like a "live fire training exercise" to much of SOCOM. That could definitely be an easy win for soon-to-be President Trump if he is ballsy enough to pull the trigger.