IIRC, the original, historical plans were developed to counter a scenario where Canada had been blitzkreige-invaded by "another Northern power", as a prelude to

IIRC, the original, historical plans were developed to counter a scenario where Canada had been blitzkreige-invaded by "another Northern power", as a prelude to launching an attack requiring the US to defend 2,000-miles of border. It never was about mistrusting Canada. Mexico, maybe, if they were mad; but not Canada.