The U.S. Navy faces a new phase of confrontation in the Strait of Hormuz, not against Iran's conventional warships, most of which now sit at the bottom of the sea, but against thousands of small, fast attack boats operated by the Islamic Revolutionary Guard Corps. President Donald Trump's blockade of Iranian ports, announced after weekend ceasefire talks in Islamabad collapsed, was set to begin Monday at 3 p.m. UK time, and the IRGC has made clear it intends to resist.
The threat is real and specific. Iran claims a fleet of 3,000 to 5,000 speedboats, many armed with missiles, rockets, and torpedoes. The IRGC has already warned over marine radio that any vessel attempting to pass through the strait without Revolutionary Guard permission risks being destroyed. And despite the devastation inflicted on Iran's traditional navy, U.S. Central Command reported sinking more than 155 Iranian vessels by April 6, the paramilitary force built to control the strait remains largely intact.
That is the hard reality confronting American destroyers as they move to enforce the blockade. Washington has won the conventional naval fight decisively. But the asymmetric one, mines, drones, and fast boats launched from hidden coastal bases, is just beginning.
Operation Epic Fury has been devastating to Iran's surface fleet. By early March, four of Iran's primary surface combatants were likely sunk or crippled. Iran lost six of its seven frigates, both corvettes, and one of its three ocean-going submarines. The Daily Mail reported that satellite imagery and military footage show widespread destruction, including the IRIS Dena, torpedoed by a U.S. submarine near Sri Lanka, killing at least 87 of roughly 180 people aboard, and the IRIS Shahid Sayyad Shirazi, a stealth catamaran capable of launching anti-ship and surface-to-air missiles.
The Revolutionary Guard's largest drone carrier in the Persian Gulf, the Shahid Bagheri, was also hit. American forces deployed two of four available aircraft carriers, the USS Abraham Lincoln and the USS Gerald R. Ford, with a third on the way. An estimated 30 percent of America's Arleigh Burke-class destroyers are in theater, along with B-1 and B-2 bombers.
Gen. Dan Caine, chairman of the Joint Chiefs of Staff, described the scope of the campaign two weeks into the war. Artillery soldiers and Marines were "sinking ships, destroying depots, and launching Army Tactical Missile Systems" and "Precision Strike Missiles," he said. American troops even used a ballistic missile system to sink Iranian warships, including a submarine.
None of that has stopped the IRGC from threatening the strait.
Iran's shift to asymmetric naval warfare is not improvised. It dates back to April 1988, when the U.S. destroyed much of Iran's fleet in a single day of combat. Tehran learned the lesson and spent decades building a doctrine focused on controlling commercial shipping rather than challenging American warships head-on.
The result is a fleet designed for confined waters. The Seraj-1, based on the British-made Bradstone Challenger, can reportedly reach speeds between 63 and 83 mph. IRGC Commander Ahmad Vahidi has stated that the Seraj-1, with its fiberglass bodywork, "can shoot rockets and it is equipped with an electronic navigation system." It also has radar-evading capabilities.
The Ashura boats carry heavy machine guns and multiple rocket launchers. The Zulfighar, described as the first air-defense speedboat, can carry four Nawab anti-air missiles in vertical launching cells. The Peykaap I is a fast torpedo boat classified as a stealth craft, equipped with 12.7mm machine guns and two torpedo tubes.
These vessels can be launched from hidden coastal bases carved into rocky terrain. Iranian state media released footage early in the conflict showing underground tunnel networks packed with naval drones, anti-ship missiles, and sea mines. The boats are harder to detect and far harder to eliminate than conventional warships.
When Trump warned Iran of a stronger military response if the regime rejected a deal, Tehran's answer was not to stand down its speedboat fleet, it was to reinforce the very doctrine that makes the strait so dangerous.
Beyond speedboats, the IRGC has deployed waterborne drones and threatened to mine the strait's main shipping channel. Some drones struck the Safesea Vishnu tanker in an Iraqi port on March 11; other vessels near Oman and Iraq were also hit. Naval drones were first showcased by the Revolutionary Guard about a year ago, and similar technology has been used by Iran-backed Houthi forces in Yemen.
Iran is believed to possess thousands of sea mines deployable from small boats or even fishing vessels. While their use in the strait has not been confirmed, the IRGC warned vessels to consult the Revolutionary Guard for safe passage along new routes near Iran's coastline, the first indication Tehran may have deployed them, a possibility previously raised by U.S. officials.
The threat alone has paralyzed commercial traffic. When a temporary ceasefire took hold after Trump struck a two-week deal with Tehran to reopen the strait, only four ships crossed on the first day, compared with more than 100 daily crossings before the war. Iranian officials later told mediators they would limit crossings to roughly a dozen ships per day.
Captains have refused orders to transit the waterway. Roughly a fifth of the world's oil supply typically passes through the strait, and the disruption has driven benchmark crude above $100 a barrel for the first time since 2022. Prices surged more than 7 percent Monday morning in Asian trade, the dollar jumped, and U.S. stock futures fell following Trump's blockade announcement.
Since February 28, at least 50 strikes have been carried out against shipping in the Gulf and the strait. Iran has attacked more than two dozen commercial ships in the Persian Gulf, demonstrating its ability to disrupt traffic without relying on large naval vessels.
The tension was captured in a purported radio exchange between the IRGC and the crew of the USS Frank E. Petersen Jr. (DDG-121), published by Iran's state-controlled broadcaster IRIB. U.S. Central Command confirmed Saturday that two guided-missile destroyers, the Petersen and the USS Michael Murphy (DDG-112), transited the waterway to "ensure the strait is fully clear of sea mines." It marked the first such transit during the conflict.
In the recording, an IRGC serviceman addressed the American warship directly:
"Navy warship 121. This is Sepah (IRGC) Navy station. You must alter course and go back to the Indian Ocean immediately. If you don't obey my order, you will be targeted."
An American voice responded calmly: "This is coalition warship 121 engaged in transit passage in accordance with international law. No challenge is intended to you."
The recording, which appears to have been edited, continued with the Iranian serviceman issuing a "last warning" three times. He then broadcast to all vessels in the Oman Sea:
"Attention all vessels in Oman Sea, this is Iranian Sepah Navy, if you see any warship in your vicinity keep a distance more than 10 miles from them because I am ready to open fire on them, without any warning."
That is the posture the IRGC is projecting as the blockade begins. Whether it follows through is the open question. But the collapse of ceasefire talks in Islamabad left no diplomatic off-ramp in sight.
After weekend negotiations between Washington and Tehran ended without agreement, Trump announced the Navy "will begin the process of BLOCKADING any and all ships trying to enter, or leave, the Strait of Hormuz." CENTCOM later confirmed the blockade would apply to ships going to or from Iran, including all Iranian ports.
The Vance-led talks in Islamabad had represented the best chance at a negotiated resolution. Their failure means the confrontation now moves from diplomatic channels back to the water.
The U.S. has the firepower. Two carrier strike groups, dozens of destroyers, strategic bombers, and a demonstrated willingness to sink anything flying an Iranian naval ensign. But the IRGC's asymmetric fleet, small, fast, dispersed, and hidden, presents a different kind of problem. You cannot sink what you cannot find until it is already shooting.
Iran's broader information warfare adds another dimension. The Justice Department recently dismantled an Iranian cyber propaganda network targeting Americans, a reminder that Tehran fights on multiple fronts simultaneously.
The international fallout continues to widen as well. Pope Leo XIV publicly clashed with the White House over the Iran war, illustrating how the conflict has rippled far beyond the Persian Gulf.
Iran built this doctrine for exactly this moment, a confrontation with a superior conventional force in the narrow waters it has spent decades preparing to defend. The IRGC's speedboat swarms, mine-laying capability, and drone arsenal were designed not to win a fleet engagement but to make passage through the strait so costly and unpredictable that adversaries think twice.
The Wall Street Journal reported that the IRGC force Tehran relies on to control the strait is thought to remain largely intact. That assessment, if accurate, means the most dangerous phase of the naval conflict may be ahead, not behind.
The U.S. Navy has proven it can destroy Iran's conventional fleet. The harder question is whether it can keep the strait open against an enemy that fights from tunnels, fishing boats, and speedboats doing 80 miles per hour.
Iran chose this fight. America has the obligation, and the capability, to finish it. The strait belongs to international commerce, not to a regime that mines shipping lanes and threatens tanker captains over the radio.
