I suspect it's an evolving requirement. The maritime warning mission I think was originally established to address coastal approaches to the east and west coasts of North America, and was only recognized in the course of events to be effective in the north as well. That's a responsibility that is of concern to both the United States and Canada. The maritime warning mission can cooperate there.
Obviously, to prosecute a maritime target, you need something, a ship or some capability to manoeuvre on water, that gives you the ability to do that. We talked briefly about the coast guard. There's the offshore patrol ship project that will ultimately produce vessels that will have some capability in that regard as well.
The real question, from the point of view of actually prosecuting a target, is how more willing are we to increase our ability for surface combatants or for surface ships to do that? From a NORAD perspective, it's the surveillance that matters, be it surveillance from fighters or maritime patrol aircraft that input information into it, or from space-based assets like the RADARSAT constellation mission when it's fielded.