Once again, it depends on the nature of the threat.
For example, in the case of NORAD, we have complete control of what we do in our own airspace in peacetime. The commanders are Canadians, the military controllers are Canadians, the aircraft are piloted by Canadians.
We were talking about a response on the west coast. Having an agreement with NORAD enables us to respond very quickly, but that does not mean that we do not have sovereignty, since Canadians are involved in the decisions.
In terms of the most probable scenarios, we are capable of completely defending ourselves. If there were an international emergency, for example, a scenario where the extreme right set off a third world war, we would have to join forces with our allies to deal with the threat.