Not difficult at all. A few tunnels, a couple of bridges. Try to remember, Manhattan is an island. An old Hagstrom map of the area shows more information than any group of terrorists could ask for in regards to shutting down Manhattan.
Granted stopping deliveries to Queens and Brooklyn would be more difficult difficult, requiring more bridges, but it’s still possible.
I did an outline for a story I was going to write ( which I subsequently junked because of the possible danger it could cause) that easily described how vulnerable NYC, Manhattan really is.
That was about 30 years ago. I doubt if there have been many security improvements since then.

So the City is costing Trump 370 Million dollars . 🤔. I wonder how much the Truckers are going to cost the City??
And don’t go off about what it’s going to cost the Truck drivers, that’s a moot point.
Prices are going to go up for what does get into the city.
Blocking access into the city is extremely easy and a few stalled trucks in the most strategic spots could bring the city to a standstill.
So what’s likely to happen?
Will more truckers join in and avoid the larger cities?
Will the government finally crack, declare Martial Law and attack the citizenry?
Will raised prices in the cities bring about more rioting?
Will the government, having declared Martial Law, seize control of all the trucks and put illegal immigrants in the driver seats?
Will this administration go down in history as the one that removes the “UNITED” in United States Of America??