Your soldiers don't fight for Canada because the U.S. provides your defense. That's why its a little disappointing to see Canadians tell the U.S. it will continue to be the biggest deadbeat in all of NATO with no attempt in the future to change that status. And then call Americans every vile name that the software filter lets through as thanks. 
And of course you don't have the ability to fight for Canada. For starters you may very well need a navy. And don't forget you will need planes that are better than your refurbished ones and a lot more. You could militarize your coast guard but then you incur the cost of providing a gun to someone on each of the boats.