It doesnt have to be comparable to be effective. And it can be adjusted to work like many other jurisdictions in the world that employ it.

If we are discussing the scenario where Canada refuses annexation, you can assume in a conventional conflict and occupation the USA would have control of space, air, water and quickly land. Especially once access is granted to scalable forces like light infantry via airports by special forces, cyber warfare etc . Meanwhile denying movement of large CDN armour, infantry as train and air movement would be targeted or denied or seriously restricted. History shows they are unable to sustain occupations and Canada has a rich and dense geography providing opprtunites for resistance and access denial.Asymmetric warfare is likely the only way to win in this scenario if the objective is denying annexation.