Iran’s military loaded naval mines onto vessels in the Persian Gulf last month, raising concerns in Washington that Tehran was positioning itself to potentially block the Strait of Hormuz, U.S. officials revealed. The move followed Israeli airstrikes on Iranian territory and signaled the risk of a dangerous escalation in regional conflict.

According to two U.S. officials familiar with classified intelligence, the mine-loading activity occurred after Israel’s June 13 missile attack on Iran. While the mines were not deployed, their presence on Iranian naval vessels suggested Tehran may have been readying for a possible closure of the strait — a critical waterway for global energy trade.

Roughly 20% of the world’s oil and natural gas shipments pass through the Strait of Hormuz. Any disruption to traffic through this narrow channel would have a significant impact on global markets and energy prices. Although oil markets initially feared the worst, prices have fallen more than 10% since U.S. strikes targeted Iranian nuclear sites, partly due to relief that maritime shipping remained uninterrupted.

On June 22, following the U.S. bombing of three major Iranian nuclear facilities, Iran’s parliament reportedly supported a proposal to shut the strait. However, that resolution was non-binding and final authority rests with the Supreme National Security Council.

It remains unclear exactly when the mines were loaded or whether they have since been removed. The U.S. did not disclose how the intelligence was obtained, though such information is typically gathered through satellite imagery or human sources.

Asked about the development, a White House official praised recent U.S. actions in the region, stating:
“Thanks to the President’s execution of Operation Midnight Hammer, the successful campaign against the Houthis, and our maximum pressure strategy, the Strait of Hormuz remains open, freedom of navigation is secure, and Iran’s capacity has been diminished.”

Neither the Pentagon nor Iran’s delegation to the United Nations provided immediate responses to inquiries.

Bluff or Real Threat?

U.S. officials have not ruled out the possibility that Iran’s mine-loading was a calculated show of force rather than a concrete step toward closure. Tehran may have intended to pressure Washington without actually obstructing the strait. Alternatively, the preparations could reflect Iran’s readiness in case a decision to block the waterway was made.

The Strait of Hormuz, just 21 miles wide at its narrowest point, is a vital corridor linking the Persian Gulf with the Gulf of Oman and the Arabian Sea. The main shipping channel is only two miles wide in each direction.

Several major oil exporters, including Saudi Arabia, the UAE, Kuwait, and Iraq, rely on the strait to deliver crude—primarily to Asia. Qatar also sends nearly all of its liquefied natural gas exports through the passage. Despite also relying on the strait for its own oil exports, Iran has long invested in the capability to close it if deemed necessary.

According to a 2019 assessment by the U.S. Defense Intelligence Agency, Iran possessed over 5,000 naval mines, which could be rapidly deployed using small, fast boats.

The U.S. Fifth Fleet, based in Bahrain, is tasked with ensuring the security of commercial navigation in the region. Traditionally, the Navy has stationed four mine countermeasure (MCM) ships there, but these have been transitioning to newer littoral combat ships (LCS), which also carry anti-mine systems.

Ahead of the June U.S. strikes on Iran, the Navy temporarily withdrew its MCM vessels from Bahrain, anticipating potential Iranian retaliation against U.S. naval assets.

Although Iran’s immediate response was limited to a missile strike on a U.S. base in Qatar, U.S. officials have warned that further retaliation from Tehran remains a possibility.