The United States military seized an Iranian container ship near the Gulf in the early hours of Monday, sending tensions spiralling hours before Washington is due to send negotiators to Pakistan for talks aimed at ending their war.

The US Central Command (CENTCOM) and President Donald Trump claimed the Touska was hit after it refused to follow US orders to withdraw from its planned passage through the Strait of Hormuz. The US has been imposing a naval blockade since last Monday

Iran has responded by describing the attack and hijack as an act of “piracy”, and threatened retribution. On Monday, hours after the attack and capture, Iran said it had no plans to send its negotiators for talks with the US in Islamabad.

This is the first non-military Iranian ship that US forces are known to have hit during the current war, and the first Iranian cargo vessel that the American military has captured since the start of its week-long naval blockade.

Here’s what we know about the capture of the ship, and why it matters:

What happened?

A little after midnight in Iran, CENTCOM announced that its guided-missile destroyer, the USS Spruance, had fired its 5-inch (127 mm) MK 45 gun at the ship’s engine room and disabled it.

According to the US military, the Touska was attempting to cross from the Arabian Sea through the Strait of Hormuz and was headed to the Iranian port of Bandar Abbas.

Since April 13, the US military has enforced a naval blockade on the Strait of Hormuz, in response to Iran blocking the passage of most vessels through the narrow waterway — except ships belonging to nations that have struck deals with Tehran.

Under its blockade, the US military is barring any ships belonging to Iran, or travelling to or from Iranian ports, from passing through the strait. In effect, this is blocking Iran’s own ships from exporting the country’s oil to other countries: According to Al Jazeera’s calculations, Iran earned nearly $5 billion in revenue from the export of oil in the month leading up to the US blockade.

According to the CENTCOM, “American forces issued multiple warnings and informed the Iranian-flagged vessel [the Touska] it was in violation of the US blockade”.

“After Touska’s crew failed to comply with repeated warnings over a six-hour period, Spruance directed the vessel to evacuate its engine room,” the CENTCOM statement said, before the American destroyer fired at the Iranian ship.

Subsequently, US Marines from the 31st Marine Expeditionary Unit clambered onto the Touska, and captured the ship. In a grainy video released by CENTCOM, US troops can be seen flying from the USS Tripoli on helicopters, then using ropes to climb down to the Touska.

What do we know about the Touska?

The container ship flies under the Iranian flag. It is 294m (965 feet) long – only a little shorter than the US aircraft carrier USS Abraham Lincoln at 332.8m (1092 feet) long.

The Touska is 32.25m (105.8 feet) wide.

The vessel and its owners have been under sanctions issued by the US Treasury Department and the US Office of Foreign Assets Control. They are accused of helping Iran break sanctions.

It is unclear what the Touska was carrying. Donald Trump posted on Truth Social that American troops are “seeing what’s on board”.

What has Iran said about the ship capture?

Early on Monday morning, Iran called the capture of the Touska an act of “piracy”.

Hours later, Iranian Foreign Ministry Spokesperson Esmaeil Baghaei told reporters that Tehran had no plans to send its negotiators to Islamabad for a round of talks that Pakistan is trying to host as early as Tuesday. The US has said that its negotiators, Steve Witkoff and Jared Kushner, are going to Islamabad on Monday for talks.

Baghaei accused the US of “violating the ceasefire” that has largely held between the US and Iran since April 9.

“Iran does not trust Washington,” he said. Asked about the US negotiators expected to travel to Islamabad, the Iranian foreign ministry spokesperson said: “There are indications from the American side that there is no seriousness on the side of the US to walk down the path of diplomacy”.

Separately, the Iranian military has said that it will hit back against the US for the ship’s seizure.

“We warn that the armed ⁠forces of the Islamic ⁠Republic of Iran will ⁠soon respond and retaliate against this armed piracy by ‌the US military,” said a spokesperson for Khatam al-Anbiya, Iran’s joint military command.