The United States has tightened the sanctions noose around Iran’s petroleum industry by blacklisting 12 tankers that enable what Washington calls Tehran’s “illegal” oil sales, as part of its ongoing maximum pressure campaign.

The US Treasury Department said in a statement on February 25 that the vessels sanctioned by the Office of Foreign Assets Control were part of a “shadow fleet” that had collectively transported hundreds of millions of dollars’ worth of Iranian petroleum and petrochemical products.

The department accused the ships of serving as “the regime’s primary source of revenue.”

The so-called shadow or dark fleet refers to vessels that move sanctioned oil while switching off their transponders to avoid detection.

Since returning to office in January 2025, US President Donald Trump’s administration has steadily slapped fresh sanctions on Iran’s oil sales network, targeting dozens of tankers, intermediary companies and buyers in a bid to mount pressure on Tehran and push it to negotiate a deal over its nuclear programme.

On February 4, 2025, Trump signed a memo revive the maximum pressure policy against Iran, pursuing a dual-track approach of diplomacy alongside threat, pressure and coercion.

The latest sanctions were announced on the eve of a third round of talks between Iran and the United States in February.

In the past years, almost all of Iran’s oil exports, now around 1.5mn barrels per day, have ended up in China, where small private refiners receive the shipments with generous discounts of up to $10 per barrel.