Iran’s military leadership warned on April 13 that no port in the Persian Gulf or Gulf of Oman would remain secure if the United States proceeds with a naval blockade targeting Iranian shipping, raising the risk of a wider maritime confrontation across key regional waterways.

In a statement carried by state-linked media, the spokesperson for the Khatam al-Anbiya Central Headquarters said maritime security in the region must apply to all or to none, warning that any threat to Iranian ports would trigger reciprocal measures.

Trump said on April 12 that U.S. forces would “seek and interdict every vessel in International Waters that has paid a toll to Iran” and would prevent ships from entering or leaving the Strait of Hormuz.

“No one who pays an illegal toll will have safe passage on the high seas,” Trump added.

U.S. Central Command later clarified that the blockade—set to begin on April 13 at 10 a.m. ET—would apply specifically to vessels entering or exiting Iranian ports, not to broader commercial traffic moving through the strait.

Iran has described the move as an unlawful restriction on international waters and warned of wider consequences.

Zolfaqari described the U.S. actions as “piracy” and said Tehran would continue to enforce its own rules governing passage through the Strait of Hormuz, including barring vessels affiliated with “enemy forces” while allowing others to transit under Iranian regulations, according to a Telegram post from Iran’s semi-official Mehr News Agency.

Zolfaqari’s statement also indicated that Iran intends to establish a “permanent mechanism” to control access to the strait even after the current conflict ends.

Iran’s latest warning suggested the conflict could expand beyond Hormuz to other critical maritime routes, including ports across the Gulf and potentially the Bab el-Mandeb Strait at the southern entrance to the Red Sea, a vital corridor for shipping between Europe and Asia.

While it assesses the threat level in the Strait of Hormuz as “critical,” the UK Maritime Trade Operations (UKMTO) said in an April 12 advisory update that the Bab el-Mandeb Strait remains at a “moderate” threat level.

“While regional tensions and Houthi rhetoric toward commercial shipping continue, there have been no confirmed incidents affecting maritime traffic in the area,” UKMTO said.

Iranian Navy Commander Rear Adm. Shahram Irani said Tehran was closely monitoring U.S. military movements in the region and dismissed Washington’s blockade threat as ineffective, according to Iran’s semi-official Tasnim News Agency.

The escalating rhetoric follows weeks of conflict that began on Feb. 28 with U.S. and Israeli strikes on Iranian targets, triggering retaliatory actions and widespread disruption to shipping and energy markets.

Emirati Minister of Industry Ahmed Al Jaber said in a post on X that as of April 12, hundreds of commercial vessels remained stranded in or near the Strait of Hormuz, including nearly 400 oil tankers.

UKMTO said in its April 12 advisory that just four vessels had transited the Strait of Hormuz in the previous 24-hour period, down from an average of 138 per day prior to the outbreak of hostilities.

Two oil tankers linked to Iran exited the Gulf via the strait on April 13 ahead of the planned U.S. blockade, according to shipping data from Kpler and LSEG.

The tanker Auroura is laden with Iranian oil products while the New Future tanker is carrying diesel loaded from the Hamriyah port in the United Arab Emirates, Kpler data showed.

Trump’s blockade announcement came shortly after U.S. Vice President JD Vance said that negotiations with Iranian officials in Pakistan had failed to produce a breakthrough, particularly on Tehran’s nuclear program.

U.S. gasoline prices have climbed significantly since the start of the conflict, reflecting the global ripple effects of instability in the Gulf. Oil prices jumped after the U.S. threat to block Iranian ports, with Brent crude futures trading at about the $102.6 mark as of 6:32 a.m. ET, on the ICE exchange in Europe, per TradingView data.

With both sides signaling readiness to escalate and no immediate diplomatic breakthrough in sight, analysts say the confrontation risks evolving into a prolonged crisis with implications for energy markets.

“The market is now largely back to conditions before the ceasefire, except now the U.S. will block the remaining up to (2 million barrels) Iranian-linked flows through the Strait of Hormuz as well,” MST Marquee analyst Saul Kavonic said.

“The key remaining question is if the U.S. renews strikes on Iran, raising the risk of strikes on energy infrastructure across the region which could have a further lasting impact beyond the duration of the war.”