From Canada's Globe and Mail. Speaks for itself.
First approved in 1930, Joint Army and Navy Basic War Plan - Red was drawn up to
defend the United States in the event of war with Britain.
It was one of a
series of such contingency plans produced in the late 1920s. Canada, identified
as Crimson, would be invaded to prevent the Britons from using it as a staging
ground to attack the United States.
But having successfully captured Canada,
the military planners had no intention of giving it up. "Blue [the Americans']
intentions are to hold in perpetuity all CRIMSON and RED territory gained," they
wrote in an appendix
It starts with a seaborne assault on Halifax to cut Canada off from its British ally. A later version, approved in 1935, allowed for first-strike use of poison gas and strategic bombing of the city, if necessary.
It also posits that the U.S. invading forces take out Niagara Falls, seize Sudbury's strategic nickel mines, capture Winnipeg as the critical east-west rail juncture and attack Vancouver to deprive the British of a West Coast maritime base