Yes, I would expect kinetic action (missiles and SOF) before very long. I also anticipate he'll continue to engage in political provocations of Canada in hopes of engineering some kind of diplomatic incident.
That seems less likely than annexing small parcels of land, bit by bit. If there's some Canadian farmland with a meth lab on it, I could see the American coast guard seizing it for 'national security' It would put Canada in an uncomfortable position since Canada hasn't had to worry about defending its border in anyone's lifetime.
It doesn't need to be Coast Guard, specifically, as long as it's a group people don't associate with war (eg: Forest Service, Law Enforcement, etc). A stand off between Canadian Mounties and American Park Rangers would result in fewer heart attacks than soldiers in army jeeps.