War Plan Red

Invasion of Canada. Bombing raids on British industrial interests. Naval blockade. Chemical weapons. Six million troops fighting on the Eastern seaboard. This wasn't a crazy Nazi plan. It was the United States' strategy to destroy Britain as a world superpower.

How the US Planned to Destroy Britain Just a Few Years Before World War II.  It actually sounds like this was a lot more than just an elaborate contingency plan, since the US had already built three disguised airfields in Canada for War Plan Red.