Iran Deploys Small Submarines to Strait of Hormuz Amid Ongoing Conflict

On May 10, 2026, Iranian Navy commander Rear Admiral Shahram Irani stood before an audience of naval officers at a ceremony honoring sailors killed aboard the frigate IRIS Dena and made an announcement that rippled through global shipping markets: Iran's domestically built midget submarines were operating inside the Strait of Hormuz in a "trigger-ready" state [1]. The submarines, which Iranian naval command internally calls the "dolphins of the Persian Gulf," represent the last major undersea capability in Tehran's arsenal after U.S. strikes destroyed its three Russian-built Kilo-class boats earlier this year [2].

The announcement raised immediate questions about what these small vessels can actually do, whether they change the military balance in the Gulf, and what their deployment means for global energy flows through the world's most consequential maritime chokepoint.

The Fleet: What Iran Has Underwater

According to the International Institute for Strategic Studies (IISS), Iran operates at least 16 Ghadir-class midget submarines, though estimates have ranged between 10 and 21 active boats over the past several years [3]. Each vessel measures 29 meters long with a 2.75-meter beam, displaces 117 tons surfaced and 125 tons submerged, and carries a crew of seven [4].

Source: International Institute for Strategic Studies

Data as of May 1, 2026CSV

The Ghadir class entered service in 2007 and was built by Iran's Marine Industries Organization with significant design input from North Korea's Yono-class program [5]. Iran first procured submarine technology from Pyongyang in the 1980s, and the Ghadir is effectively a domestically produced evolution of the North Korean design [6].

Each boat is armed with two 533mm torpedo tubes capable of launching Valfajr heavyweight torpedoes, Hoot supercavitating torpedoes, and — according to some assessments — Jask-2 anti-ship cruise missiles developed specifically for submarine launch [3]. Beyond strike capability, the class can lay naval mines covertly and insert or retrieve combat divers [4].

Iran also retains one Fateh-class coastal submarine, a larger indigenous design displacing roughly 527 tons, and one Nahang-class midget boat [3]. Its three Kilo-class submarines — the IRIS Taregh, IRIS Nooh, and IRIS Yunes, purchased from Russia in the 1990s — were confirmed destroyed during Operation Epic Fury in early March 2026, with at least one struck at its pier in Bandar Abbas [7]. The loss eliminated Iran's only blue-water submarine capability and made the Ghadir fleet the centerpiece of its undersea strategy by default.

Why the Strait of Hormuz Matters

Before the current conflict, approximately 20 million barrels per day of crude oil and petroleum products transited the Strait of Hormuz, accounting for roughly 20% of total global petroleum consumption and 25-27% of all seaborne oil trade [8]. China and India combined received 44% of crude exports passing through the strait [9].

Source: U.S. Energy Information Administration

Data as of Dec 1, 2025CSV

These volumes dwarf every other maritime chokepoint. The Strait of Malacca handles about 12.5 million barrels per day; the Suez Canal and SUMED pipeline together move 7.1 million [8]. A credible threat to Hormuz traffic affects not just oil prices but the liquefied natural gas supply chains that countries like Japan and South Korea depend on for electricity generation.

Since the U.S.-Israeli air campaign against Iran began on February 28, 2026, shipping through the strait has been reduced by an estimated 95% [10]. The disruption has been driven less by direct military interdiction than by the collapse of the commercial insurance market underpinning maritime trade through the region.

The Insurance Weapon

Within 48 hours of the February 28 strikes, war-risk insurance premiums for vessels transiting the strait surged fivefold [11]. Major marine insurers then terminated existing coverage entirely, offering replacements at roughly sixty times pre-crisis rates [10]. The Additional War Risk Premium climbed from approximately 0.05% of a vessel's hull and machinery value to a peak of 2.5% in early March — an increase that translates to millions of dollars per transit for a very large crude carrier [12].

Source: S&P Global / Insurance Journal

Data as of May 6, 2026CSV

By late March, premiums had partially stabilized around 1% of hull value, still eight times pre-war levels [12]. As of May 6, 2026, they sit at roughly 0.75% [13].

The London insurance market's Joint War Committee expanded its listed area of high-risk waters to include waters around Oman [11]. This designation alone can trigger contractual clauses in charter agreements, giving shipowners the right to refuse passage or demand additional compensation.

Historical precedent suggests that insurance costs, not naval combat, are what actually close shipping lanes. During the 1980-1988 Tanker War between Iran and Iraq, 451 attacks on merchant vessels initially reduced commercial shipping by 25% and spiked crude prices [14]. But the strait never fully closed, partly because Iran itself depended on the sea lanes for its own oil exports [15]. The current situation differs because Iran's export capacity has already been degraded by sanctions and strikes, reducing its economic incentive to keep the strait open.

The threshold at which insurance surcharges trigger large-scale rerouting around the Cape of Good Hope — adding 11,000 nautical miles and 10 to 14 days per transit — appears to have been crossed early in the crisis [16]. Multiple shipping companies have already shifted routes, absorbing higher fuel costs rather than paying war-risk premiums that can exceed $3 million per voyage [12].

'Vulnerable to Detection': The Military Assessment

Defense analysts have been blunt about the Ghadir's limitations. The submarines lack air-independent propulsion (AIP) — a technology that allows diesel-electric boats to remain submerged for weeks without surfacing. Without AIP, Ghadir crews must periodically raise a snorkel mast to run diesel generators and recharge batteries, creating a detectable radar cross-section and thermal signature [1].

"They eventually have to come up and snorkel," one analyst told Fox News. "This will make them more vulnerable to detection and destruction" [1].

The U.S. Fifth Fleet, headquartered in Bahrain, maintains multiple layers of anti-submarine warfare (ASW) capability in the region. P-8A Poseidon maritime patrol aircraft carry sonobuoy dispensers and magnetic anomaly detectors optimized for tracking diesel-electric submarines [17]. Surface combatants deploy towed array sonars, and MH-60R Seahawk helicopters carry dipping sonar systems, including the AN/AQS-22 airborne low-frequency sonar [18].

However, the geography of the Strait of Hormuz complicates standard ASW doctrine. The strait is roughly 33 kilometers wide at its narrowest point, with shipping lanes just 3 kilometers across. Water depths range from 60 to 90 meters — shallow enough to create acoustic clutter that degrades sonar performance [4]. Heavy shipping traffic generates additional ambient noise. Traditional ASW systems optimized for tracking large submarines in deep, open ocean are less effective in these conditions [17].

The Ghadir's design exploits this environment. The class can conduct "bottom rest" operations — settling on the seabed with engines off, producing minimal acoustic or thermal signatures until activating for a short-range attack [4]. In these conditions, the submarines become harder to distinguish from the natural environment than they would be in open water.

The U.S. Navy has been investing in AI-assisted sonar analysis and unmanned underwater vehicles to address this gap. The AN/AQS-20C mine-hunting sonar, paired with Barracuda mine-neutralization systems, can work semi-autonomously to detect and classify underwater objects [18]. But mine countermeasures and submarine hunting are different disciplines, and the Navy's capacity to do both simultaneously in a confined waterway is finite.

The Defensive Deterrent Argument

Critics of Western framing have argued that Iran's submarine deployment is a rational defensive measure rather than an offensive provocation. The case rests on several historical facts.

In April 1988, the United States destroyed half of Iran's operational navy in a single day during Operation Praying Mantis, sinking or damaging six Iranian vessels in retaliation for a mine strike on the USS Samuel B. Roberts [15]. That episode demonstrated the vulnerability of Iran's surface fleet to U.S. firepower and, according to analysts at the George C. Marshall European Center for Security Studies, directly shaped Tehran's subsequent pivot toward asymmetric naval doctrine [19].

Since February 2026, U.S. and Israeli strikes have destroyed an estimated 150 Iranian naval vessels, including all three Kilo-class submarines and the frigate IRIS Dena [7]. Carrier strike groups have operated continuously in the Gulf throughout the conflict. From Tehran's perspective, the question is not why Iran would seek an underwater capability, but why it would fail to do so given decades of demonstrated vulnerability to conventional naval superiority.

Iran's doctrine, sometimes described as a "denial navy" by Western analysts, does not aim to control the sea. It aims to make the cost of operating in the Gulf prohibitively high for adversaries [19]. Submarines, mines, fast attack craft, and anti-ship missiles create overlapping threat layers that force a technologically superior navy to expend disproportionate resources on defense. A single Ghadir-class boat costs a fraction of the defensive measures required to neutralize it.

This logic mirrors asymmetric submarine strategies employed elsewhere. North Korea operates roughly 70 submarines — most of them small, aging coastal boats — in the Yellow Sea, where they serve primarily as a signaling and deterrence tool rather than a reliable interdiction force [6]. Russia has used Kilo-class submarines in the Black Sea to threaten Ukrainian shipping and constrain NATO surface operations, though with mixed operational results [20].

The empirical record of small-submarine sea denial is mixed. North Korea's sinking of the South Korean corvette ROKS Cheonan in 2010 — attributed to a Yono-class torpedo attack — demonstrated that midget submarines can achieve tactical surprise [5]. But such engagements are rare, and the strategic effect of submarine deployments has historically been measured more in deterrence and insurance costs than in ships sunk.

Legal and Operational Thresholds

The legal framework governing engagement with Iranian submarines has shifted significantly since the onset of active hostilities. Under the law of armed conflict, enemy warships — including submarines — are lawful targets once positively identified, and may be attacked without prior warning during an international armed conflict [21].

Professor James Kraska of the U.S. Naval War College has argued that the sinking of the IRIS Dena complied with the law of naval warfare under this framework [22]. However, debate continues over whether proper rescue obligations under international humanitarian law were met in that engagement and others [23].

The rules of engagement for U.S. forces in the Gulf are governed by Standing Rules of Engagement (SROE), supplemented by classified mission-specific rules tailored to the current conflict [21]. The specific thresholds for engaging a submarine that has not yet fired are not publicly known. During earlier periods of tension — including the 2015-2020 period when the Iran nuclear deal (JCPOA) was in effect or recently abandoned — engagement authority was considerably more constrained, requiring evidence of hostile intent rather than merely hostile capability [24].

The current state of open armed conflict has lowered those thresholds. Under status-based targeting rules applicable during international armed conflict, an Iranian military submarine can legally be engaged based on its identity alone, without waiting for a hostile act [21]. This represents a fundamental change from the pre-conflict rules of engagement, when Iranian naval vessels could approach within close range of U.S. ships without triggering a lethal response.

Who Ordered the Deployment

Rear Admiral Shahram Irani, commander of the Islamic Republic of Iran Navy (IRIN), publicly announced the submarine deployment during the May 10 ceremony [1]. The IRIN operates Iran's conventional naval forces, including the Ghadir fleet, and is distinct from the Islamic Revolutionary Guard Corps Navy (IRGCN), which controls fast attack craft, coastal missile batteries, and its own smaller watercraft [25].

The distinction matters. The IRIN is the regular navy, reporting through the military chain of command to the Armed Forces General Staff. The IRGCN reports to the IRGC and ultimately to Supreme Leader Ali Khamenei. During the current conflict, both organizations have been operating in the Strait of Hormuz, but the submarine deployment appears to be an IRIN operation [25].

The timing — during a memorial for sailors killed on the Dena — carries political weight. The frigate was sunk by a U.S. submarine in early March 2026, and the ceremony framed the Ghadir deployment as both a military response and a statement of resilience [1]. Whether the deployment was coordinated with ongoing diplomatic back-channels — several rounds of indirect negotiations have occurred through Omani intermediaries since March — is unclear from public sources. The announcement's bellicose tone suggests that the naval command, at minimum, is not signaling an imminent de-escalation.

What Comes Next

The military significance of 16 midget submarines in the Strait of Hormuz is debatable. They lack the endurance, stealth, and armament of modern conventional submarines. They are constrained by the need to snorkel. They face the most concentrated anti-submarine warfare capability in the world.

But the submarines do not need to sink a carrier to achieve strategic effect. Their presence creates uncertainty. Uncertainty raises insurance premiums. Insurance premiums close shipping lanes. Closed shipping lanes move oil prices. This chain of consequences — from a 29-meter boat with seven crew members to the price of gasoline in Tokyo — is the mechanism by which asymmetric naval power translates into geopolitical leverage.

The question for the coming weeks is whether that leverage is being wielded as a bargaining chip in negotiations or as a signal that Tehran has decided negotiation is no longer the path forward. The answer may depend less on what happens underwater than on what happens in the diplomatic channels running through Muscat.