Since we are on that topic, I would like to say that I was in the military in 2001. After the attacks, I saw American documents that mentioned that command and control of Canadian airspace was henceforth part of their Northern Command, because the Americans did not trust Canada to counter the threats. Has that changed in 15 years? Do we have sovereignty now in that respect?
On April 14th, 2016. See this statement in context.