Iran's Islamic Revolutionary Guard Corps (IRGC) navy announced on Tuesday, 9 September that its forces captured one of the US Army's most advanced unmanned submarines at the entrance of the Strait of Hormuz, in what it described as a complex intelligence and operational mission. The seized vessel was identified as a Dive-LD unmanned underwater vehicle, which the IRGC characterised as equipped with the world's most modern subsurface technology.

What the IRGC Announced

According to a statement published on the IRGC's official news outlet, Sepah News, the unmanned underwater vehicle was apprehended in a coordinated operation at the mouth of the Strait of Hormuz. The IRGC said images of the captured submersible would be released within hours of the announcement. In a separate statement issued the same day, the IRGC also claimed its air defence systems had shot down a US MQ-9 Reaper drone over the Strait of Hormuz.

The US Military's Response

Following the IRGC's announcement, the US military issued a statement acknowledging that one of its underwater drones had 'malfunctioned' more than a day earlier during a survey of regional waters. Notably, the US statement did not address whether the device had been seized by Iranian forces, leaving the two accounts in direct tension. The US military's use of 'malfunction' rather than 'capture' signals a deliberate effort to manage the diplomatic optics of the incident.

Iran's President Weighs In

Iranian President Masoud Pezeshkian addressed the broader confrontation in a post on social media platform X on Tuesday, striking a defiant but measured tone. 'The Islamic Republic of Iran has always been opposed to war and considered the preservation of the people's interests and ensuring the (West Asia) region's security to lie in refraining from warmongering,' he wrote. He added: 'However, just as it has courageously risen to defend against aggression up to this day, Iran will continue this resistance with strength until the aggressors are brought to complete regret, and will remain the guardian of the rights of the great Iranian people.'

Background: Escalation Since February

The drone seizure comes against a backdrop of sharply deteriorating US-Iran relations. On 28 February, Israel and the United States launched joint strikes on Tehran and other Iranian cities, triggering retaliatory waves of Iranian missile and drone attacks on Israeli and US targets across the region. Iran simultaneously tightened its grip on the Strait of Hormuz — a chokepoint through which roughly 20% of global oil supply transits.

A subsequent diplomatic effort produced a memorandum of understanding (MoU) signed by Washington and Tehran on 18 June, under which both sides were to conclude negotiations within 60 days — a deadline that lapsed on 17 August. The fate of those talks remains unclear, according to reports, with the latest incident likely to further complicate any resumption of dialogue.

Strategic Significance of the Strait of Hormuz

The Strait of Hormuz is among the world's most strategically sensitive waterways, connecting the Persian Gulf to the Gulf of Oman. Iran's repeated assertions of control over the strait — including drone interceptions and now a submarine seizure — represent a sustained pressure campaign on US naval operations in the region. This is not the first time the IRGC has seized or harassed US unmanned assets in the area; similar incidents have occurred multiple times since 2019, each time raising the risk of unintended escalation.