US president Donald Trump has said he is considering re-launching major combat operations against Iran and is close to a decision, telling Axios that Tehran “hasn’t received enough pain yet.”

Mr Trump’s warning came after Yemen’s Houthi fighters struck two Saudi oil tankers in the Red Sea, extending the Middle East war to a second major shipping chokepoint.

Mr Trump said he would hold Iran responsible for any further Houthi attacks, writing on social media: “If they do this again, the US will hold Iran responsible, in that the Houthis are a Surrogate and/or Proxy of Iran, and major military punishment will be inflicted upon Iran and, of course, the Houthis, themselves.”

Sources in Iran and Yemen told Reuters that Iran had flown Revolutionary Guard commanders, military advisers and missile and drone-related equipment into Yemen days before the Houthis announced their Red Sea blockade. The Houthis dismissed the report.

The US is failing to wear down Iran with strikes around the Strait of Hormuz and making no progress to resolve the conflict through diplomacy. Here are Donald Trump’s apparent options:

The US is moving special operations forces, weapons and medics to the Middle East to give US president Donald Trump broader military options as he considers widening the conflict against Iran, the Wall Street Journal reported, citing officials.

In the past week, special operations forces have deployed to the region from US bases, according to flight-tracking data and officials.

Squadrons of jet fighters have been staged across the Middle East, and bomber aircraft at bases in the US and UK are on high alert, the Journal reported.

The number of tankers crossing the Strait of Hormuz fell to just one on Thursday, the lowest since 7 May, as oil prices surged back to $100 a barrel, according to data from analytics firm Kpler.

Only the very large crude carrier New Giant, loaded with two million barrels of Iraqi Basrah crude, exited the strait on 23 July, bound for China’s Rizhao port. No ships entered the waterway that day, down from three crossings the previous day.

The US military said late yesterday it had completed a 13th consecutive night of strikes on Iran.

At the Bab el-Mandeb strait, tanker crossings rose to 32 on 23 July from 26 the day before, Kpler data showed, though some vessels are already rerouting. A clean tanker loaded with naphtha bound for Asia has turned toward the Suez Canal exit rather than the typical Bab el-Mandeb route — a detour that could make the voyage nearly three times as long. Saudi Aramco has also started offering crude cargoes loading at Egypt’s Mediterranean port of Sidi Kerir as an alternative to its Red Sea ports.

Two Chinese supertankers carrying a combined 4 million barrels of Saudi Arabian oil exited the Red Sea via the Bab el-Mandeb strait on Thursday, shipping data ⁠showed, apparently escaping a blockade of Saudi oil by Yemen’s Houthi militias.

It happened as Saudi vessels came under attack.

The Red Sea blockade by the Iran-aligned Houthis is worsening global energy supply disruption, coming at the same time the Strait of Hormuz is practically shut due to the resumption of fighting between the US and Iran.

The UK “stands ready 24/7 to defend itself”, the government has said, after Iran claimed Britain would “bear responsibility” for allowing the US to use British bases.

It comes after Iran’s Ministry of Foreign Affairs (MFA) accused the UK government of “complicity in the crime of aggression and war crimes” by allowing the US to carry out “unlawful attacks”.

While the government has refused to take part in offensive campaigns against Iran, it has allowed the US to launch defensive strikes from British bases hosting American personnel.

In a statement, the MFA said that anyone who supports “military aggression against Iran will bear responsibility for the consequences and repercussions of its decision”.

US president Donald Trump has carried out 13 consecutive nights of strikes against targets in Iran, indicating potential further escalation.

Iran flew Islamic Revolutionary Guard Corps (IRGC) commanders, military advisers and missile- and drone-related equipment into Yemen this month, according to four sources, in a move that suggests Tehran is seeking to strengthen the ability of its Houthi allies to threaten Red Sea shipping.

Four sources, two of them Iranian, Yemen’s information minister and a regional security analyst, said Iran transferred the IRGC personnel and military-related equipment on a flight from Tehran to Yemen 10 days ago.

The two Iranian sources told Reuters that between 10 and 21 IRGC personnel, including senior commanders, were on the Mahan Air flight.

The plane was originally bound for the Houthi-controlled capital Sanaa, but diverted to the Red Sea port city of Hodeidah after the airport came under attack by the Saudi-backed Yemeni government.

“The IRGC commanders travelled there to support Houthi operations and provide training on new missile systems,” one of the sources said, adding that Iran also sent gold on the aircraft to fund Houthi activities.

Donald Trump has warned Tehran that any damage to ships will be paid for by Iranian money that the US has in its possession.

“Please let this statement serve to represent, until further notice, that from this point forth, any and all damages done to Ships, Cargo, or anything related thereto, will be paid for by Iranian Money that the United States has in its possession, and controls.

“These damages may be very substantial but, nevertheless, this is the fair and equitable thing to do”, Trump wrote on Truth Social Thursday evening, Washington time.

The US has accused Iran of targeting civilian vessels in the Strait of Hormuz. Meanwhile, Yemen’s Iranian-backed Houthi rebels bombed two Saudi oil tankers in the Red Sea.