Canada is a sovereign nation, it has no obligation to accept any of those migrants. Under current agreements it would accept asylum seekers from the US, but it

Canada is a sovereign nation, it has no obligation to accept any of those migrants. Under current agreements it would accept asylum seekers from the US, but it could easily withdraw. You could have winged UAVs with small arms paroling constantly at very low time increments at any possible land entrance point, and dropping demolition satchels from helicopters is a very easy method to handle attempted landings. Or you could use the UAVs again if that gets too costly in resources. The current government would probably not try this, but a lot can change over the coming decades. I don't find this position very novel, as MAD, The Samson Option, and the Korean DMZ were considered and at least implemented in a posturing way, even if the first two are quite overblown.