The US has launched a new round of strikes on Iran after President Donald Trump signalled he'd "hit them hard again tonight" following an overnight exchange of attacks on Tuesday.
Explosions have been reported by Iranian state media in parts of the country's south, including Sirik and Bandar Abbas - port cities on the Strait of Hormuz.
US Central Command (Centcom) said the strikes were carried out to "further degrade Tehran's ability to threaten freedom of navigation" in the vital waterway.
Iran has not yet commented, but senior officials earlier warned any attack from the US would be met with an "immediate response".
Centcom added: "The United States is holding Iran accountable for recent unjustified aggression against commercial shipping and civilian crews freely navigating a vital international waterway."
Several explosions have also reportedly been heard in the southern cities of Konarak and Chabahar.
Air defence systems have been activated in Bandar Abbas, according to reports in Iranian state media.
On Tuesday, the US military said it had launched "powerful" strikes in response to attacks on three tankers in the strait.
On Wednesday, Iran said it targeted US military sites in Bahrain and Kuwait in retaliation.
Tuesday into Wednesday saw the worst exchange of strikes between the US and Iran since the deal - known as a memorandum of understanding (MoU) - was signed on 17 June.
Trump said on Wednesday that the ceasefire agreement signed last month with Iran is "over", and added the US "hit them very hard last night" and will "probably hit them hard again tonight".
In response, Iran's Foreign Minister Abbas Araghchi said in a post on X: "We do not answer vulgarity with vulgarity, but with action: fearlessly and with great valour."
The deal between the US and Iran included 14 points, among them a 60-day period for a ceasefire during which negotiations should continue, the safe passage of vessels through the Strait of Hormuz and the US lifting sanctions on Iran.
The 60-day-period for negotiations is not yet up, but Trump has said he saw further talks as "a waste of time".
These are not the first strikes since the MoU was signed.
The US launched a series of strikes on Iran on 26 June after an Iranian projectile hit a cargo ship in the Strait of Hormuz.
Further US strikes took place on 27 June, following an attack on a tanker. But later that month both sides had agreed to "stand down".
