Don't rule out contaminated food supplies.

B-b-but... actually, that might work?

Joke, but there is a vulnerability to anti-vax disinformation. As well as population declining immigration policies. A lot of gain of function/biowarfare research is focused on ethnic vulnerabilities. Collective stupidity vulnerabilities makes biowarfare easier.

“To quote The Art of War, the opportunity of defeating the enemy is provided by the enemy himself,” said Minister of Defense David McGuinty. “While this is arguably applicable to most things in the Trumpadministration, we figured it would be simplest to barricade the border and wait for the entire army to succumb to whatever virus or contaminated lettuce they could’ve eradicated months beforehand.”

The main reason Canadians did so well in the world wars was because of our culture of hunting and outdoorsmanship.

If the USA invades they will occupy the major cities easily. But to achieve their goals of resource extraction etc they will need to build infrastructure that will be easy targets for saboteurs.

You don't even need weapons since much of our topography is actively attacking our infrastructure all ready. Push some rocks, divert some water, dig a hole in the right spot, than walk away and let nature take it's course.

Not to mention all the bad food and no more food inspections or safety guidelines and oh so much more. Oh wait those are real. Never mind.

Joining the US Army when the war starts so I can cross the border and immediately defect

“Infectious diseases are always a major issue in any military encampment, let alone in a country where they only check children for 3 diseases now,” notes Michel. “In America, there are confirmed or likely cases of e coli, salmonella, diphtheria, explosive diarrhea, corrosive diarrhea, incendiary diarrhea, normal diarrhea, measles, mumps, chicken pox, bird flu, swine flu, regular flu, whooping cough, COVID-19, COVID-20, COVID Zero, hantavirus, norovirus, gigavirus, hepatitis A, hepatitis B, hepatitis 3D, and RSV. Outside of New Jersey, there may be even more.”

Gold

"Never interrupt your enemy when he is making a mistake"

-- Napoleon

Waiting sometimes is the best solution: let the problem sort itself out and you didn't have to do anything.