By the way, when America invaded "Canada", Canada was not Canada, but part of the then, British Empire". Canada was not a sovereign nation at the time, nor was it the Canada that is known today because France still owned Quebec. Your postulations using inaccurate history are about as accurate as your prognostications regarding the EU.
The US does not need to worry about Canada invading the US because Canada has no military to speak of. They don't need one and neither does much of the Western world, including NATO and EU countries, because the USA is willing to use its military on their behalf. That is why you can afford socialism, you don't need to defend yourselves because you know the US will.
The real worry America has regarding Canada, the UK and the EU is that these countries won't regard radical Islam with the caution that it deserves. You people didn't think the Nazi's were serious until they dropped a bomb on St Pauls.
Can you learn to say; "Allah be Praised"?