Iran live updates: Trump administration expands scope of secondary sanctions

President Donald Trump announced "major combat operations" against Iran on Feb. 28, with massive joint U.S.-Israeli strikes targeting military, government and infrastructure sites.

Delegations from the U.S. and Iran entered negotiations in June aimed at a war-ending deal based on a memorandum of understanding signed by both countries.

The U.S. and Iran have nonetheless continued to exchange strikes, with the strategic Strait of Hormuz as the primary flashpoint.

The U.S. Treasury is expected to expand the scope of secondary sanctions it can impose on entities and countries that maintain business ties with Iran in an effort to ramp up economic pressure, a source familiar with the plans told ABC News.

The announcement is expected Monday afternoon. Reuters was first to report the news.

The source said the action is likely to reveal ‌additional categories of Iran-related conduct that would be subject to secondary sanctions in the future, making it easier to take action against those facilitating the transactions on behalf of the Iranian government.

A senior administration official said Treasury Secretary Scott Bessent is expected to warn that any remaining financial lifelines -- including through banks and third countries that have tolerated certain activity -- must be shut down.

The official said the Treasury Department has "mapped Iran's oil-smuggling and sanctions-evasion network" and plans to present this information to countries helping Iran evade the sanctions as a warning.

Mohammad Mokhber, a senior adviser to Iranian Supreme Leader Mojtaba Khamenei, says Iran's response to U.S. sanctions will be "more decisive than ever."

A tanker was struck by an "unknown projectile" off the coast of Saudi Arabia, according to UK Marine Trade Operations.

A security officer reported the strike, which hit the main deck, causing a fire, as the ship was about 63 nautical miles off the coast of Yanbu, Saudi Arabia, UKMTO said on Monday.

"All crew are safe and accounted for and no envirnomental impact has been reported," UKMTO said on social media.

Iran will not export "a single drop of oil" as long as the U.S. continues its "economic war" again the country, an Iranian official said Sunday.

"If the economic war continues, not a single drop of oil will be exported٫ neither through the Strait of Hormuz nor from anywhere in the Persian Gulf," Mohsen Rezaee, secretary of Iran's Supreme National Security Council, posted on X .