As I understand it, the American airforce is allowed to use our airspace as part of NATO - that airbase in Newfoundland - Goose Bay is it? It's one of the biggest in the world and American aircraft are always flying in and out of it. Also, I recall an agreement signed where American jets can use Canadian airspace in the event of another terrorist attack. As for missiles on our soil, I thought we already had American missiles somewhere out in the tundra? It would probably be a good idea to have some in Canada, who knows, it may be better strategically to guard some of the northern American cities?
Also, we would be contributing funds, personnel and technology as I understand it.