So, here's my defense plan for Canada. Basic philosophy: it is unsafe to wait for an attack.
1. Get public confirmation from NATO that Article 5 applies even if the aggressor is also a NATO member.
2. Send an ultimatum to Washington demanding a public acknowledgement of Canadian sovereignty by the President and confirmation of non-aggression.
3. In the absence of that acknowledgement, sever diplomatic ties, close the borders, and embargo trade. Blow bridges, tear up roads and rail lines.
The point of these steps is that we don't benefit from delay. If it's going to happen, we need to start getting ready immediately, and not spin our wheels hoping for some change in policy.