The United States have a poor war record since World War 2 – when it had allies (allies that it now threaten under the new regime).
Since WW2 the US
- lost in Korea (1950-53)
- lost in Vietnam (1962-73)
- won in the Persian Gulf (1991)
- played to a draw in Iraq (2003-2011)
- lost in Afghanistan (2001-2021)

If the US were to invade Canada it would be waging war not only on Canada but on the rest of the NATO allies that they would be betraying.
Individually none of them have a larger standing army than the US, but collectively they do.
That is the entire point of NATO – to protect the security and freedom of its member countries.
It boggles my mind how Trump could betray NATO and threaten either Canada or Denmark when they can’t even win a war even WITH their former NATO allies.
Question:
Could the US defeat Canada (and by extension all of NATO) WITHOUT allies?