US intel: Iran prepared to block Hormuz with naval mines after Israeli strikes

Iran prepared to potentially blockade the Strait of Hormuz by loading naval mines onto military vessels in the Persian Gulf last month, according to two U.S. officials familiar with classified intelligence.

The move, which has not been previously reported, occurred shortly after Israel’s missile strike on Iranian territory on June 13 and raised alarm in Washington over the risk of a major escalation.

The officials, speaking to Reuters on condition of anonymity to due to the sensitive nature of the intelligence, said that while the mines were not deployed, their presence on Iranian vessels suggested Tehran may have been seriously considering a closure of the strategically vital waterway — a move that could have crippled global oil and gas flows and intensified the already dangerous regional conflict.

Roughly 20 per cent of the world’s oil and gas supplies pass through the Strait of Hormuz, and any disruption would likely cause a sharp surge in energy prices. However, global oil benchmarks have dropped more than 10 per cent since U.S. airstrikes on Iranian nuclear sites on June 22 — a decline fueled by relief that the hostilities did not impact energy transit routes.

That same day, Iran’s parliament reportedly endorsed a resolution in favour of closing the strait. While symbolic, the measure was non-binding and would ultimately require approval from Iran’s Supreme National Security Council. Iranian state media, Press TV, emphasised that only the council could authorise such a decision. Over the years, Tehran has often threatened to shut down the strait but has never acted on the threat.

U.S. intelligence has not confirmed whether the mines remain aboard the vessels or have since been removed. It also remains unclear precisely when the loading occurred during the back-and-forth airstrikes between Israel and Iran. The method by which U.S. agencies gathered the intelligence was not disclosed, but such assessments typically rely on satellite imagery, surveillance, and human intelligence.

Some U.S. officials believe the mine-loading operation may have been a strategic bluff — a calculated show of force to suggest that Tehran was prepared to act, without any intention of doing so. Others believe Iran’s military may have been preparing for a genuine contingency in case top leadership ordered the closure.

Responding to inquiries, a White House official praised recent U.S. actions in the region. "Thanks to the President’s brilliant execution of Operation Midnight Hammer, successful campaign against the Houthis, and maximum pressure campaign, the Strait of Hormuz remains open, freedom of navigation has been restored, and Iran has been significantly weakened," the official stated.

The Pentagon declined to comment on the matter. Iran’s mission to the United Nations also did not respond to requests for comment.

Strategic chokepoint

The Strait of Hormuz — which separates Iran and Oman — is just 21 miles (34 kilometres) wide at its narrowest point, with a navigable shipping channel only two miles wide in each direction. It connects the Persian Gulf to the Gulf of Oman and the Arabian Sea, serving as the primary export route for oil and gas from major producers in the region.

OPEC members, including Saudi Arabia, the United Arab Emirates, Kuwait, and Iraq, rely on the strait for the bulk of their crude oil exports, much of it bound for Asian markets. Qatar, one of the world’s largest exporters of liquefied natural gas (LNG), also sends nearly all its shipments through the strait. Even Iran exports most of its crude oil via this route — a fact that has historically tempered Tehran’s threats to close it.

Nonetheless, Iran has long invested in the capability to shut the strait if it deems necessary. According to a 2019 estimate by the U.S. Defence Intelligence Agency, Tehran possesses more than 5,000 naval mines, which could be quickly deployed using fast boats and other naval assets.

The U.S. Navy’s Fifth Fleet, based in Bahrain, is tasked with safeguarding maritime commerce in the region. Typically, the Navy maintains four mine countermeasure (MCM) vessels in Bahrain, although those are now being phased out in favour of littoral combat ships (LCS), which also possess mine-clearing capabilities. In the lead-up to the June 22 U.S. strikes, all MCM ships were temporarily withdrawn from Bahrain as a precaution against a potential retaliatory strike on the fleet’s headquarters.

Despite initial fears, Iran’s immediate response was limited to a missile strike on a U.S. military base in neighbouring Qatar. However, U.S. officials continue to monitor the situation closely and have not ruled out further retaliatory actions by Tehran.

By Tamilla Hasanova