War Plan Red has been known for years. Although the plan was declassified in 1974, the 1935 Army war games were fairly open that they were based on war with Great Britain involving an invasion of Canada. Every couple of years, it gets pulled out, usually by a left wing Canadian professor who wants to use it to tar Canadian conservatives as making common cause with the hated Americans. About 8 years ago, it was even argued that the location of Fort Drum in upstate New York was to prepare for an invasion of Canada (instead of being a pork barrel project by Senator D’Amato).
It is no surprise it comes up now. Canada is in the midst of a general election and the liberals are performing badly. This could be 3-5% to the Liberals (or at least away from the Tories).