yes, and the american colonies also invaded Montreal in 1775, just prior to the american revolution, albeit ultimately an unsuccessful campaign
of course, there are any number of proposed war scenarios studied by the military, all in esoteric theory
no doubt north american history is full of conflict and strife, but with WW1, WW2, and the Cold War, i think our nations have come to mutual understandings
"1902" is a treaty between japan and britain, not the start of the plan. The plan was approved in 1930 and modified in 1935. WWII started 4 years later. Just think, had britain and japan joined forces montreal could be a u.s. city right now.War Plan Red was created because Americans knew Britain was locked in a strategic alliance with Japan, the Anglo-Japanese Alliance of 1902. American planners thought that Britain’s imperial reach would bring it into conflict with the US. In 1935 War Plan Red was updated and specified which roads to use in the invasion.
Needless to say Canada had a similar plan updated through the 1930's to invade the U.S.