I don't know the source of your information on directed landing, but I can tell you there was one case with a Korean airliner on April 11, 2012, where there was a bomb threat on board that aircraft. That aircraft was met by a NORAD response, which happened to be U.S. F-15s out of Washington state. It was escorted and landed in Comox. That's the only one that I'm aware of, so you'd have to provide me more specificity.
We train for Operation Noble Eagle weekly. I have been in scenarios, and there are public office holders in government who have trained on these scenarios as well, because we could conceivably make a recommendation to government to shoot down an aircraft. We train regularly with our U.S. counterparts that I'm involved with. I would say, from an aerial perspective of domestic terrorism, we take that into account. Our F-18s will be part of that response, but NORAD has other tools in place.
I don't have an assessment of domestic terrorists as our largest threat. When I think of threats—and I tend to look at existential ones above that—I don't see that as the largest threat. I see the threat of the business that I'm in, and that's responding in support of Canadian sovereignty.
The domestic threat piece is not unique to Canadian Armed Forces. It's a law enforcement responsibility, by and large.