That's actually insanely/disturbingly easy:
1 -- Our rail-system goes through one of [fewer than] 16 points in all lengthy runs -- destroy or control those locations and you have control of *ALL* rail-shipping.
2 -- Raise the price of Diesel fuel by another dollar (maybe even as little as 50 cents) and It's likely that a lot of trucking companies will go out of business.
Do both of those and there will be starvation. There are other things that our government can do to exacerbate starvation-enforcement.
Your comment reminded me of this article I read this morning:
What the Looming Port Strike Is Really About