Sea mines are described as “simple, uncool weapons” by Scott Savitz, a naval marine warfare expert at RAND who was stationed in Bahrain in 2001. These weapons, which predate World War I and have seen little advancement, resemble the spiky metal spheres often depicted in films. They are small enough to be easily concealed in a fishing boat and are packed with TNT and ammonium nitrate.
However, their detonation can split ships in half, according to Savitz. He notes that they typically have a “much greater effect than a missile” and can cause millions of dollars in damage for a cost of only a few thousand dollars each. Their effectiveness is significant, with naval mines accounting for 77% of all U.S. Navy ship casualties since 1950, according to the Strauss Center at the University of Texas.
As the conflict with Iran enters its 13th day with no resolution in sight, Iran is reportedly turning to older technology to enhance its standing in a war that has thus far been characterized by hypersonic missiles. While not flashy, the sea mine could currently be Iran’s most potent weapon against the United States.
Some U.S. intelligence officials have indicated to CNN that Iran has begun deploying mines in the Strait of Hormuz, a critical chokepoint through which a fifth of the world’s oil passes and the focal point of the current standoff between Iran and the U.S. In recent days, Iran has targeted several oil tankers in and around the Strait, including two Iraqi oil tankers in the Persian Gulf that resulted in one fatality. Commodity expert Rory Johnston estimates that nearly a quarter billion barrels of crude oil per day have been stranded in the Gulf since the conflict began nearly two weeks ago. Crude oil prices have surged, trading just under $100 a barrel at the time of writing, and gasoline prices have risen by 20% due to the blockage. The repercussions extend across the Pacific, with Pakistan implementing school closures and four-day work weeks, India shutting down restaurants and hotels nationwide to conserve oil for cooking, and Thailand urging government employees to avoid using elevators.
Savitz clarifies that Iran is not technically “closing” the Strait of Hormuz. Instead, he explains, “It’s the decision of individual users whether or not they are willing to bear the risk. If they can raise the risk, or the perceived risk, to a level such that commercial traffic decides that they will not go through that strait, then that’s sufficient.”
The current level of risk in the Strait has already deterred most major marine war insurers, who have withdrawn coverage for ships operating there. Freight rates have reached record highs, with a very large crude carrier traveling from the strait to China potentially earning half a million dollars in revenue daily. However, if Iran has indeed laid mines in the Strait, this would transform a temporary blockade into a far more intractable problem.
The psychological warfare of the sea mine
A significant reason for the power of sea mines lies in their “disproportionate psychological effects,” designed to exploit the fear of the unknown. These mines are nearly invisible throughout their lifecycle and are exceptionally difficult to detect, unlike missiles which can be identified by heat signatures or radar trails. A mine’s deployment is simple: a vessel can drop one overboard and depart unnoticed. As Savitz puts it, “There’s a splash in the water. Ships are dropping things in the water all the time.”
The psychological impact is further amplified by certain mine programming. Some mines are designed to allow the first few ships to pass safely before detonating on a later vessel, potentially targeting a mine-clearing team and the tanker following behind it.
Ship operators often face a dilemma, as Savitz explains: they either “say, ‘Well, I can’t see it, so I’m just going to ignore it’ and blindly find themselves in trouble,” or they “say, ‘Well, the waters might be mined,’ and they overreact and are unwilling to assume any risk from mines, even as they’re assuming other types of risk.”
Some of the most severe incidents have resulted from the latter reaction. During the Tanker War of the 1980s, Iran and Iraq attacked 450 ships in the Persian Gulf, with mines proving to be their most destructive weapon. In 1988, ten U.S. Navy sailors were severely injured when the USS Samuel Roberts struck an Iranian M-08 mine, a design dating back 80 years. Savitz notes that “All three of the US warships that were damaged by mines in 1988 and 1991 did not know they were in a minefield when it happened.” The U.S. response was Operation Praying Mantis, the largest American naval surface battle since World War II, which resulted in the sinking of half of Iran’s operational navy in a single afternoon. The cost of repairs reached $90 million, for a weapon estimated to be worth approximately $1,500.
Despite having decades to prepare since that incident, “The U.S. has been underinvesting in mine warfare for many decades,” according to Savitz. The Navy decommissioned its last dedicated minesweepers in the Persian Gulf in September of the previous year. Their intended replacements were littoral combat ships, a program Savitz described as “a disaster” due to their construction of small metal vessels that could themselves trigger mines, unlike traditional wood and fiberglass minesweepers.
Furthermore, mines are considered too unglamorous to secure budget allocations. “A hypersonic missile is exciting and gets attention. Mines don’t.” The last time a U.S. warship was damaged by a mine was in 1991.
Hormuz escalation
The question remains whether the conflict in the strait will escalate to such a degree. Savitz expresses cautious optimism, stating, “Yes, we will be able to get it open.” He points to the U.S. capabilities, including divers, unmanned systems, allied minesweepers from Europe, and even Navy dolphins trained for mine detection. However, the timeline for resolution is contingent on other concurrent developments. Mine countermeasures forces operate slowly and predictably, navigating waters that may also be subject to Iranian missiles, explosive boats, and drones. Savitz poses the critical question: “Can we suppress those threats well enough that mine countermeasures forces can operate without undue hindrance? That’s the challenge.”
Even under optimal circumstances, mine clearance is an extremely slow process. Savitz estimates the cost ratio between laying and clearing mines to be “between one and three orders of magnitude”—meaning it can be up to a thousand times more expensive to remove a mine than to deploy one.
A rapid clearance, creating a single narrow passage for tankers, could be achieved in days, Savitz suggests. Reaching a level of safety that reassures tanker operators might take weeks. However, fully clearing and sweeping the entire waterway to ensure complete confidence that no mines remain could take significantly longer, or may never be fully accomplished. Mines from World War II still exist in the Baltic Sea and the Pacific Ocean due to incomplete cleanup efforts.
Ultimately, the risk-reward calculation will shift. During the Tanker War, ships continued to transit minefields. Savitz notes that approximately 1% were hit, “but the risk was deemed to be justified by the reward.”