Operation Economic Outcast is a United States sanctions campaign targeting Iran's oil trade and the networks that keep it running. It returned to the headlines this week after Washington sanctioned two Mumbai-based companies.

On October 9, the U.S. sanctioned SSPL Solutions Private Limited and Samudra Marine Services Private Limited, along with five Indian nationals. Washington alleged their involvement in the trade of petroleum products from Iran.

Such designations typically freeze any U.S.-linked assets and bar American firms from dealing with the targets. Secondary sanctions can also punish non-U.S. companies that do business with them.

Iran has long relied on shadow shipping networks to sell oil despite sanctions. Middlemen, ship-to-ship transfers and shell companies help disguise the cargo's origin.

India is one of Iran's traditional energy partners, which is why Indian entities sometimes appear in these actions. New Delhi has not commented on the latest designations.