Beneath the Surface: The Naval Mine Crisis in the Strait of Hormuz

The Strait of Hormuz is currently facing a complex crisis following Iran’s deployment of a large number of naval mines during recent hostilities. Although Iran announced on 17 April 2026 that the strait is open, this declaration appears largely political rather than operational. Estimates of the number of mines vary significantly, ranging from around 5,000 mines according to Iranian figures to between 10,000 and 12,000 mines according to U.S. assessments. The strait normally carries about 20 million barrels of oil per day, representing roughly 20% of global energy flows, yet traffic has collapsed from approximately 140 ships per day before the crisis to only 7 ships shortly after the reopening announcement. This sharp decline illustrates that the core issue is not political permission to transit, but whether ships can safely pass through a heavily mined environment.

Naval mines are deployed using methods that prioritize speed and volume rather than precision. Iran relies heavily on hundreds of small, fast attack boats, each capable of laying dozens of mines in a single mission, meaning that thousands of mines can be deployed within days. These operations are often conducted under wartime pressure, frequently at night, and without precise mapping. As a result, the minefield in Hormuz appears dense and irregular, rather than systematically organized. Some mines are anchored to the seabed, while others are designed to drift. Due to strong currents in the strait, drifting mines can move several kilometers from their original deployment points, making their locations increasingly uncertain over time and turning the area into a dynamic and unpredictable hazard.

The mines deployed fall into three main categories, each increasing in complexity and danger. The simplest are contact mines, which detonate upon physical impact with a vessel. More advanced are influence mines, which can detect a ship through changes in its magnetic field, acoustic signature, or water pressure, allowing detonation without direct contact. The most sophisticated are advanced systems such as the Maham-series. For example, the Maham-3 weighs approximately 300 kilograms and can operate at depths of up to 100 meters, while the Maham-7 weighs around 220 kilograms and is optimized for shallow waters. Both rely on magnetic and acoustic sensors and are designed with shapes that make them difficult to detect using sonar. These advanced mines represent the most serious threat due to their ability to remain hidden and selectively target vessels.

Although Iran deployed the mines, it may not be able to remove them efficiently. Statements by Abbas Araghchi referring to reopening the strait “with technical constraints” suggest that Iran does not have precise knowledge of all mine locations. This can occur when mines are deployed rapidly without proper documentation or when operational conditions during conflict disrupt coordination. Additionally, environmental factors such as currents can cause mines to drift away from their original positions. As a result, even Iran may be unable to identify and clear all mines quickly, effectively transforming them from a controlled weapon into an uncontrolled and shared hazard.

Detecting naval mines is extremely challenging and cannot be done easily. Radar, which operates using radio waves, is ineffective underwater, meaning the United States must rely on sonar systems. Sonar works by emitting sound waves and analyzing their reflections to map the seabed and identify objects. However, this process is slow and requires careful analysis. A single mine countermeasure vessel may only be able to clear a few square kilometers per day. The difficulty is compounded by the fact that mines are often designed to blend into the seabed, while natural objects such as rocks and debris create false signals. In addition, drifting mines can reintroduce danger into areas that were previously cleared. For these reasons, detection is a time-intensive and technically demanding process.

Mine removal is carried out through a structured process known as mine countermeasure operations. After detecting and identifying a mine, it is typically neutralized using unmanned underwater vehicles (UUVs) such as Knifefish, which can place explosive charges near the mine. In some cases, specialized divers are used, although this is highly risky. Airborne systems, including the AN/ASQ-235 (Archerfish) deployed from MH-60S helicopters, provide additional capability for targeting mines. Mine-clearing ships are built with low magnetic and acoustic signatures to avoid triggering mines. These operations require significant resources, including more than 20 specialized vessels, continuous air cover, and naval protection. Rather than attempting to clear the entire strait immediately, the U.S. strategy focuses on establishing safe corridors, allowing limited but controlled navigation while broader clearance continues.

Yes, the scale of the challenge makes international involvement necessary. European countries, including the United Kingdom, have discussed participating in mine clearance operations, particularly in coordination meetings such as those held in Paris. According to Donald Trump, multiple countries are expected to contribute to reopening efforts. This reflects the global importance of the strait, as disruptions affect not only regional actors but also global energy markets, shipping costs, and supply chains.

Mine clearance is inherently slow. Clearing a relatively small minefield can take between 21 and 53 days, but the situation in Hormuz is far more complex. With potentially 5,000 to 12,000 mines spread across a narrow yet heavily trafficked waterway, full clearance could take several months or longer. The timeline depends on factors such as the number of available vessels, environmental conditions, and whether mines continue to drift. Even under optimal conditions, the process cannot be significantly accelerated without increasing risk.

A political agreement, such as ongoing discussions in Islamabad, does not automatically mean that the strait will reopen in practical terms. While a settlement may reduce military tensions and allow clearance operations to proceed more safely, the mines themselves remain in place. This means that reopening will likely occur in stages, beginning with limited safe corridors and gradually expanding as more areas are cleared. In other words, political decisions may enable reopening, but they do not eliminate the technical constraints.

The situation in Hormuz demonstrates a fundamental asymmetry in naval warfare. Naval mines are relatively cheap and easy to deploy, allowing thousands to be laid within days, yet they are extremely difficult and time-consuming to remove, often requiring months of sustained effort. In this case, the reopening of the strait is not determined by political declarations alone, but by the slow and methodical process of detecting and neutralizing each individual mine.

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