My concern is that other countries can aid Iran with weapons in a direct and indirect way. There is no guarantee to block the railroads from East and the shipments from North.
I would be more concerned if more countries did not help Iran, since in this conflict it's the victim.
That's not a concern it's a reality. Iran is not shut-off or blockaded to any meaningful degree. It has tons of unmolested border crossings and Caspian sea access, and maintains full control within it's own borders (minus the parts that have been blown up).