Tehran has vowed to respond to a suspected Israeli air strike on its consular building in Damascus

Robert Wright in London, Bita Ghaffari in Tehran and James Shotter in Jerusalem 

Iran’s elite Revolutionary Guards have seized an Israeli-linked container ship in the latest escalation of hostilities between the Islamic republic and Israel.

The capture of the MSC Aries (IMO No 9857169, L366mxB51mxd12.2m) comes as Tehran has been vowing to respond to a suspected Israeli air strike on Iran’s consular building in Damascus this month that killed seven guards members, including two senior commanders.

Video published online showed two guards soldiers sliding from a helicopter down ropes on to the deck of the 366m-long container ship in the Gulf of Oman.

The vessel is operated by Geneva-based Mediterranean Shipping Company, the world’s biggest container shipping line. It is owned by Gortal Shipping, a finance company affiliated with Zodiac Maritime, a company controlled by Israel’s Ofer family.

Hours later, US President Joe Biden cut short a weekend beach trip and was returning to the White House to consult with his national security team about the situation in the Middle East, the White House said.

The US military has repositioned two destroyers in case they are needed to help respond. One was already in the region and one was redirected to bolster the US presence, according to officials. One includes an Aegis missile defence system. 

Biden said on Friday that he expected Iran to mount an attack against Israeli interests “sooner rather than later”. It was not clear whether the seizure of the Aries represented the full retaliation.

A spokesman for Israel’s military said that its forces were on full alert and that “dozens” of planes were airborne in preparation for any attack.

Israel also said that from 11pm local time on Saturday, gatherings would be limited to 1,000 people, and school activities would be cancelled. The cabinet was due to meet later on Saturday.

Israel Katz, Israel’s foreign minister, accused Iran of conducting a “pirate operation”. 

IRNA, Iran’s state news agency, said the guards’ naval forces had captured the ship after boarding it using a helicopter.

The seizure took place in the Gulf of Oman, close to the critical chokepoint of the Strait of Hormuz, a vital maritime trade route through which much of the world’s crude shipments pass.

Iranian leaders have blamed Israel for the April 1 strike on its diplomatic mission and likened it to a direct strike on the republic. The assault has raised concerns over the risk of a full-blown regional war erupting.

Hostilities across the region have intensified since Hamas’s October 7 attack on Israel killed 1,200 people, according to Israeli officials, and triggered the war in Gaza.

Iranian-backed militants have launched drones, rockets and missiles against Israel and US troops in the region as Israeli forces have mounted a retaliatory offensive against Hamas in Gaza, which has killed more than 33,000 people, according to Palestinian officials.

Iran has sought to avoid a direct conflict with Israel and the US, and has signalled that its response to the April 1 strike on its consular building will be calibrated.

Iranian forces have previously seized tankers during periods of heightened tension with the US and other western states.

The seizure of the MSC Aries is the first in waters off Iran since January, when Iranian forces seized the Greek-owned oil tanker St Nikolas in a similar position.

MSC confirmed that the vessel had been seized by “Iranian authorities”.

The ship was operating a service for MSC from the United Arab Emirates port of Khalifa to Nhava Sheva in Mumbai.

“She has since been diverted from her itinerary towards Iran,” the company said. It added that the ship had 25 crew on board. “We are working closely with the relevant authorities to ensure their wellbeing, and safe return of the vessel,” MSC said.

The UK’s Maritime Trade Operations office, based in Dubai, reported that the vessel had been “seized by regional authorities”.

A bulletin on the incident from Ambrey, a UK maritime intelligence company, said that Zodiac had encountered “Iranian hostile acts” in the past because of its Israeli ownership.

“Israeli-owned shipping is advised to reconsider transiting the Strait of Hormuz,” Ambrey wrote.

India said 17 of its nationals were on board the Aries. “We are in touch with the Iranian authorities through diplomatic channels, both in Tehran and in Delhi, to ensure [the] security, welfare and early release of Indian nationals,” an official said.

The waters of the Strait of Hormuz, near where the MSC Aries was seized, are the world’s most important route for oil tankers, carrying oil from Saudi Arabia and other Gulf producers to the wider world. They are also an important route for container ships going to and from Khalifa and the vast container port at Jebel Ali, in Dubai.

Container ships have mostly stopped sailing through waters off Yemen since December, after Iranian-backed Houthis launched a series of attacks on vessels linked with Israel, the UK and US, claiming to be acting in support of Gaza’s Palestinians. However, the route through the Strait of Hormuz had not until now been as big a concern.

Guy Platten, secretary-general of industry lobby group the International Chamber of Shipping, called the seizure of the MSC Aries a “flagrant breach of international law and an assault on freedom of navigation”.

“This reprehensible attack against a merchant ship once again places innocent seafarers on the front lines of geopolitical conflict,” Platten said.

Peter Sand, chief analyst at Xeneta, a shipping intelligence service, said an already bad situation in the Red Sea and Gulf of Aden had “got worse”.

The vessel’s seizure could put containerised imports into the Gulf region and oil exports at risk, Sand added.