Iran official says support for new sanctions would be an 'act of war,' and other Middle East news

The head of Iran’s top security body says Tehran will see any country’s support for new U_S_ economic measures against the Islamic Republic as an “act of war."

The new head of Iran's top security body warned Sunday that Tehran will see any country's support for new U.S. economic measures against the Islamic Republic as an “act of war,” while Iran's president defended a memorandum of understanding with the United States as the best way out of the stalled conflict .

Treasury Secretary Scott Bessent on Monday is expected to announce the new measures after the U.S. vowed to impose an “unprecedented” level of economic warfare and isolation on a country that has lived for decades under sanctions . Also Monday, Pakistan’s army chief is expected to visit Iran as mediators try to revive talks.

Meanwhile, attacks calmed on the Strait of Hormuz but posturing did not, as a recently created Iranian authority listed dozens of vessels it said will face restrictions on future transits.

Here’s a look at the latest developments in the Iran war and the wider Middle East on Sunday.

The hard-line leader of Iran’s Supreme National Security Council, Mohsen Rezaei, issued his latest warning on X, with the comments quickly shared by Iranian state media.

It came a day after Rezaei's most extensive public comments since being named to the post this month.

“If (Trump) wants to do something, we will retaliate in a seismic manner,” he had told the state broadcaster in an interview that aired late Saturday. He said Iran would target other oil-shipping routes from the Persian Gulf — alternatives to the Strait of Hormuz.

Rezaei, a former Revolutionary Guard commander and military adviser to Supreme Leader Ayatollah Mojtaba Khamenei, was part of senior appointments widely seen as hardening Tehran’s political and military stance.

Iranian President Masoud Pezeshkian earlier Sunday said the memorandum of understanding signed in mid-June was the best way to move beyond a situation of “neither war nor peace," adding that Tehran can’t attract investment nearly six months after the war began.

“There is not a single provision in this agreement that amounts to capitulation,” Pezeshkian said in a speech published by state-run IRNA. “The supreme leader sets the policies, and we will follow that path.”

The interim deal opened a 60-day period for talks aimed at ending the war and reaching an accord on Iran's nuclear program . That period ended last week with no signs of compromise or extension.

There were no confirmed attacks in the Strait of Hormuz over the past 48 hours, a multinational coalition overseen by the U.S. Navy said Sunday, with shipping traffic still at reduced levels. The U.S. military said its blockade of Iranian ports had redirected 70 commercial ships and disabled three as of Sunday.

Iran's recently created Persian Gulf Strait Authority, sanctioned by the U.S ., published a list of dozens of ships it said had violated arrangements for transiting the strait and would face future restrictions like fines or seizures. The strait had been considered an international waterway before the U.S. and Israel attacked Iran on Feb. 28.