The US Treasury Department announced fresh sanctions Tuesday targeting Iran's oil exports and the shipping networks that move its crude, following Secretary Scott Bessent's pledge to impose the "toughest sanctions" yet on Tehran. The measures aim to squeeze Iranian revenue.

Bessent said last week that the administration would broaden pressure on Iran's energy sector, focusing on tankers, front companies and foreign buyers accused of helping Tehran evade existing restrictions. The Office of Foreign Assets Control published named entities and vessels as the designations took effect.

Iran's Foreign Ministry rejected the threat on Sunday, describing Washington's approach as "desperate" and predicting the sanctions would fail. Tehran has repeatedly said it can sustain oil sales to Asian buyers, chiefly China, despite years of US restrictions on its crude trade.

The designations intensify friction between Washington and Tehran at a time of broader regional tension. European governments and China, which continues to purchase discounted Iranian oil, are likely to face renewed US pressure to curb dealings with sanctioned firms.

Analysts at the Washington-based Foundation for Defense of Democracies argue that enforcement against so-called shadow-fleet tankers is central to any effective pressure campaign. Critics contend that additional measures will do little to change Tehran's calculations.