IPs owned by Iranian entities could be blocked straightforwardly by network operators at various levels. They could probably fudge the paperwork via Russian or Chinese entities and obfuscate the routes with cooperation from Russian/Chinese network operators, but that would take time.

they're fudging the paperwork with oil tankers that everybody can see https://www.reuters.com/graphics/IRAN-OIL/zjpqngedmvx/

They said "tunnel"