Both countries are subject to U.S. sanctions.

"Banks and economic actors can now use infrastructures including non-SWIFT interbank systems to deal in local currencies," Iran's state media has declared. 

Moscow has lately been cozying up to Tehran, with Iran revealing in November it will provide Russia with Su-35 fighter jets, Mi-28 attack helicopters and Yak-130 pilot training aircraft.

The global de-dollarization drive has been going on for years with BRIC countries and the so-called pariah states trying to ditch the American dollar in favor of other currencies. 

Back in 2019, Putin declared that time was ripe to review the dollar's role in trade. At that time, Russia and China considered switching to the euro, the world's second most dominant currency, as an acceptable stalemate, with the ultimate goal being to use their own currencies.