US forces began striking Islamic Revolutionary Guard Corps (IRGC) targets in Iran at midday Eastern time on September 1, US Central Command (CENTCOM) said.

The ongoing strikes are the latest escalation of the war between Washington and Tehran centred on the Strait of Hormuz after more than a month of relative calm and increased sanctions targeted at the Iranian economy. The strikes are also part of a breakdown of the June memorandum of understanding meant to wind down the conflict, keeping the world's most important oil chokepoint at the heart of a standoff that has repeatedly drawn in Iran's Gulf neighbours.

CENTCOM said the action followed recent attempted IRGC attacks on commercial shipping in the strait and on American service members in the region; Iran has yet to confirm.

Iranian state media reported explosions in the southern cities and ports of Bandar Abbas, Chabahar, Konarak, Qeshm and Sirik. The reports could not be independently verified.

The strikes came days after the US hit the Iranian island of Larak on August 30 and 31, after which Iran directed attacks at US military targets in Jordan and the UAE. President Donald Trump had threatened to strike Iran "very hard" in an interview with Fox News.

Iran has gone about seven weeks without shipping significant crude exports through the Strait of Hormuz for the first time on record, as a US naval blockade cuts off one of Tehran's main sources of foreign-currency earnings, Reuters reported. Tehran has tied any reopening of the strait to an end to US strikes and the blockade.

Iranian officials framed the earlier exchanges as a shift in Tehran's deterrence posture. "The message is clear: the might of its armed forces will ensure enemy regret," Ebrahim Azizi, chairman of the Iranian parliament's National Security and Foreign Policy Committee, said on X.

The war began on February 28, when the US and Israel launched strikes on Iran and killed Supreme Leader Ali Khamenei. Iran responded by closing the Strait of Hormuz, through which about 20% of the world's oil and gas passed before the conflict.

The Assembly of Experts named Mojtaba Khamenei, the late leader's son, as supreme leader on March 8.

The latest strikes came as US Treasury Secretary Scott Bessent, at a G20 meeting, signalled further sanctions on banks the administration alleges facilitate business with Iran.