Sometime before dawn on May 3, 2026, a bulk carrier transiting the Strait of Hormuz was swarmed by multiple small craft operating near Iranian waters. The vessel reported the attack to the United Kingdom Maritime Trade Operations center and kept moving. The next day, a tanker north of Fujairah, the major bunkering port on the Gulf of Oman side of the strait, was hit by unknown projectiles. Neither ship’s name, flag state, nor cargo has been publicly confirmed. What is confirmed is that these were not isolated events. They were the latest in a campaign of fast-boat raids that has made the world’s most important oil chokepoint a combat zone.
Since February 28, 2026, Iran’s Islamic Revolutionary Guard Corps Navy has used its fleet of small, heavily armed speedboats to harass, board, and fire on merchant vessels passing through the strait. The International Maritime Organization has verified 21 attacks on commercial shipping since the crisis began. The UN Office at Geneva, drawing on UKMTO data, puts the broader count at at least 41 incident reports, a figure that includes boardings, near-misses, and projectile strikes still awaiting full verification. The 26 ships referenced in reporting on this crisis falls between those two institutional counts, reflecting attacks where physical contact or weapons impact has been documented but not yet cleared through the IMO’s stricter review process.
What the ‘mosquito fleet’ actually is
Western naval planners have used the term “mosquito fleet” for decades to describe Iran’s swarm-warfare capability. The IRGC Navy operates hundreds of small fast-attack craft, many of them fiberglass-hulled boats under 15 meters long, capable of speeds above 40 knots. Types include the domestically produced Peykaap class, armed with rocket launchers and machine guns, and older Boghammar-type boats that Iran has been modifying since the 1980s Tanker War. The boats are cheap to build, easy to hide among fishing traffic, and stationed at bases and island garrisons scattered across the strait, including Bandar Abbas, Abu Musa Island, and Larak Island.
The tactical logic is simple: overwhelm a larger adversary with numbers and speed in confined waters where big warships cannot maneuver freely. A U.S. destroyer can track and engage a handful of fast boats, but when dozens fan out across a shipping lane barely 21 nautical miles wide at its narrowest, packed with tankers, container ships, and fishing dhows, the geometry turns ugly. Firing on small craft in congested waters risks hitting civilians, and sinking boats that scatter after an attack requires positive identification of each one as hostile. The IRGC exploits that hesitation deliberately.
The U.S. Maritime Administration has issued a formal advisory describing how Iranian forces have historically used small boats and helicopters to board commercial vessels or force them into Iranian territorial seas. That same advisory now warns of added threats from missiles, unmanned aerial vehicles, and unmanned surface vessels, meaning the fast-boat swarms are only one layer of a broader asymmetric toolkit that also includes shore-based anti-ship cruise missiles and explosive drone boats.
Why the U.S. Navy cannot simply eliminate the threat
The United States maintains a carrier strike group and associated escorts in the region, along with Cyclone-class coastal patrol ships and Mark VI patrol boats better suited to close-quarters work. But the math does not favor the defender. The strait handles roughly 20 percent of the world’s seaborne oil trade, with dozens of large vessels in transit at any given time. Protecting all of them simultaneously against hit-and-run raids launched from multiple directions is a coverage problem, not a firepower problem.
Rules of engagement compound the difficulty. Sinking Iranian boats preemptively would constitute an act of war against a state that maintains it is exercising sovereignty over its territorial waters. Engaging boats after they attack requires rapid identification in a waterway where legitimate Iranian fishing vessels, coast guard cutters, and commercial traffic operate constantly. The IRGC Navy’s boats often carry no visible markings and can blend back into port traffic within minutes of a strike.
This is not a new dilemma. During the 1987-1988 Tanker War, the U.S. Navy conducted Operation Earnest Will to escort reflagged Kuwaiti tankers through the Persian Gulf. Even with dedicated convoy escorts, Iranian small boats and mines damaged multiple vessels, including the frigate USS Samuel B. Roberts. The current situation is arguably harder to manage because the IRGC’s fleet is larger, its boats are faster, and the addition of drones and unmanned surface vessels creates threats that did not exist 40 years ago.
What the institutional record shows
The IMO Council convened an emergency session on March 18 and 19, 2026, and formally condemned threats and attacks on shipping, calling for a safe-passage framework tied to UN Security Council Resolution 2817. The Council’s language invoked freedom of navigation principles and demanded protections for civilian seafarers. That framing matters: it signals that the international community views the small-boat campaign as a violation of longstanding maritime law, not a gray-zone nuisance that can be managed quietly.
The IMO Secretary-General, briefing foreign ministers, referenced fatalities and stranded seafarers but did not publish granular casualty figures broken down by incident and nationality. Crew testimonies, which would provide the clearest picture of what these attacks look like from the bridge of a tanker, have not appeared in any official record reviewed for this article. The people absorbing the most risk in this crisis, the largely migrant crews who sail these ships, remain almost invisible in the public record.
Attribution also remains partially unresolved. The MARAD advisory describes Iranian tactics in general terms but does not publish a ship-by-ship forensic breakdown linking each incident to a specific IRGC unit or vessel type. The UKMTO report on the May 4 tanker attack noted “unknown projectiles,” leaving open the possibility that the strike came from a shore-based launcher or drone rather than a fast boat. Until flag states or naval intelligence agencies release detailed after-action assessments, the precise ratio of small-boat attacks to other weapon types will remain an estimate.
Consequences already in motion
For shipowners and charterers, the fallout is immediate. War-risk insurance premiums for Strait of Hormuz transits have climbed sharply since March, according to industry reporting from Lloyd’s List and the Baltic Exchange, and some underwriters are requiring 72-hour notice before binding coverage. Operators have begun adjusting transit times to daylight hours, sailing in loose convoys when possible, and in some cases rerouting cargoes entirely. Each of those measures adds cost and delay to supply chains already under strain.
On the bridge, masters are revising passage plans and ship security assessments in real time. The MARAD advisory recommends heightened vigilance, rapid communications with naval authorities, and rehearsed responses for situations ranging from suspicious approaches to attempted boardings. Bridge teams are maintaining near-constant watch in waters where fishing vessels, tugs, and legitimate small craft can be indistinguishable from potential attackers until the final moments before contact.
Diplomatically, the IMO Council’s call for a safe-passage framework tied to a Security Council resolution signals that the crisis has moved beyond the “isolated incidents” phase. Gulf states that depend on oil exports through the strait may welcome stronger security guarantees but resist arrangements they see as infringing on sovereignty. Naval powers want clearer rules of engagement that allow them to deter swarm attacks without triggering a wider war. And the safety of civilian seafarers, the issue that should anchor every policy discussion, continues to compete for attention against oil prices, alliance politics, and the broader geopolitical contest with Tehran.
What comes next in the strait
The pattern since February points in one direction: escalation, not de-escalation. The pace of reported incidents accelerated through April and into May 2026. The IRGC has shown no sign of pulling its boats back to port, and the addition of drone and missile threats suggests Iran is layering capabilities rather than relying on any single tactic. The U.S. Navy and its partners can raise the cost of individual attacks through closer patrols and faster response times, but they cannot eliminate the threat without a political settlement or a military campaign that no government appears willing to undertake.
For the crews still transiting the strait, the calculus is grimmer and more personal. They sail through a chokepoint where verified attacks are counted in the dozens, where the boats that hunt them are too small and too numerous to be swept from the water, and where the international community has condemned the violence but not yet stopped it. The institutional record is clear enough on the scale of the problem. What it does not yet answer is how many more ships have to be hit before the response matches the rhetoric.
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*This article was researched with the help of AI, with human editors creating the final content.
