I'm sure Europe might be able to rig up something to threaten the Soviets even without the USA and Canada. (I have an idea for that in a someday upcoming TL, where the whole face of the geopolitical world is changed- from a Cold War in Europe and a Cold Peace with the USA (thanks to Presidents Wallace and Taft), a near European WWIII in the 1960's (with spies, missile silos in Wales, and JFK as a reporter), and a USSR breakup in the 1980's- and a UK-Canada-Australia-New Zealand vs. USA-Argentina-various other American nations war over the Falklands. All thanks to a British spy noted for his non-spying accomplishments being a few second too late...)