The first answer is that we're vulnerable. The north warning system is out of date and, in fact, it's too limited to deal with the 360-degree threat environment that North America faces.
Government tends to talk about NORAD modernization as equivalent to modernization of the north warning system. It's much bigger than that. It's about North American defence modernization and developing a group of new sets of sensors, both land, sea, air and space-based, and developing the computer capabilities, the processing of analytical capabilities to be able to integrate an all-domain defence requirement. The F-35 is an important step forward, but it's only one step of thinking about the need for a much more complicated, complex, layered defence capability, one that has to move farther north.
All of these are major issues when we talk about dealing with the vulnerabilities that Canada faces in conjunction with our close ally, the United States, in trying to ensure that our deterrent, the Western deterrent, the U.S.-led deterrent, the global deterrent, is not undermined because of vulnerability at home.
Potential adversaries like Russia can hold Canadian populations as hostage, which would then reduce the willingness of governments in Canada and elsewhere to respond to deter these threats overseas.
Those are the two key elements in my mind.