On the other hand, Russia was rumored to have been secretly buying Iranian oil previously and then reselling it as their own to European countries. Why couldn't they do it all over again?
After all, the US has no access to the Caspian Sea to check that trade (unlike the Persian Gulf)
This is the first time I am hearing about it. How can Iran smuggle oil to Russia, when dozens of American military satellites are scanning every square inch of the Russo-Iranian border? Also, I don't think that Russia will take the risk of dishonoring the UN sanctions.