Sanctions do not penalize non-U.S. refiners from buying Iranian crude, but they make it hard for foreign banks to pay the Islamic Republic the hard currency that makes up around 50 percent of government revenue. Just this week, Indian refiners began paying around $5 billion of oil debts after struggling for seven months to find a way to get money to Tehran.
Washington wants to isolate Tehran over its nuclear program, which it believes Iran is using to develop weapons. Tehran says it needs nuclear power.
South Korea is one of Iran’s top crude buyers, importing around 230,000 barrels per day on average, based on total imports in the first half of the year. Its refiners are paying Iran for oil into bank accounts in South Korea.