Editor's Note: This is part two in a three-part series examining Iran's ability to close the Strait of Hormuz. Iran knows its navy is no match for the ubiquitous and powerful U.S. Navy, so any credibility Iran may have in its threat to close the Strait of Hormuz rests on its asymmetric assets like small speedboats and more conventional weapons like anti-ship missiles and naval mines. In this segment, Stratfor considers the option of mine warfare. Click to read Part 1 and Part 2.
Relatively cheap, cost effective and easy to deploy, mines are the improvised explosive devices of naval warfare, and the potential variations in the Iranian mine arsenal are practically limitless. Could Iran close the Strait of Hormuz with an impenetrable field of naval mines? Probably not, but it wouldn't have to. In mine warfare, the ultimate objective is often psychological.
Perhaps even less clear than the composition of Iran's anti-ship missile arsenal is its stockpile of naval mines. Over the years, Tehran has amassed thousands of mines, largely from Russia and China. Many are old free-floating and moored contact mines, which must physically make contact with a ship's hull in order to detonate. But Iran has also acquired more advanced naval mines that have complex and sensitive triggers — some can be detonated by acoustic noise, others by magnetic influence from the metal of a ship's hull. When deployed, many of these mines rest on the sea floor (for better concealment) and are designed to release what is essentially a small torpedo, either guided or unguided.
Iran also is thought to manufacture naval mines indigenously, and this is the real problem for mine-clearing operations in the Strait of Hormuz. Naval mines need not be particularly complex or difficult to build to be effective (though a long shelf life ashore and longevity in the maritime environment are important considerations and require a detailed understanding of naval mine design). Relatively cheap, cost effective and easy to deploy, mines are the improvised explosive devices of naval warfare, and the potential variations in the Iranian mine arsenal are practically limitless. The question is not how many modern mines Iran has acquired but what Iran has improvised and cobbled together within its own borders and manufactured in numbers. Although old, poorly maintained naval mines and poor storage conditions can be a recipe for disaster, many of Iran's mines may have been modified or purpose-built to suit Iran's needs and methods of deployment.
These methods of deployment extend far beyond Iran's small number of larger, purpose-built mine-warfare ships. Not only have fishing dhows and trawlers been modified for mine-warfare purposes, but the naval arm of the Islamic Revolutionary Guard Corps (IRGC) is known to have a fleet of small boats not just for swarming and suicide attacks but also to be employed to sow naval mines.
Because of the uncertainty surrounding Iran's mine-laying capability as well as its naval mine stockpile, it is as impossible to estimate the effort it would take to clear Iranian mines from the strait. It all depends on what plays out, and there are many scenarios. One envisions Iran surreptitiously sowing mines for several days before the U.S. military detects the effort. Another has Iran deploying mines after an initial American strike, in which case Iran's mine-laying capability would be severely degraded. The question of which side moves first is a critical one for almost any scenario.
But it is reasonably clear that Iran lacks both the arsenal and the capability for a "worst-case" scenario: sowing a full offensive field across the Strait of Hormuz composed of tens of thousands of mines that would effectively prevent any ship from entering the waterway. Though the IRGC and other forces that could be involved in mine-laying operations certainly practice their craft, their proficiency is not at all clear. And though the Iranians have a variety of mine-laying vessels at their disposal, their ability to perform the precise navigation and coordination required to lay a large-scale minefield with its hodgepodge of purpose-built minelayers, modified dhows and barges and small boats is questionable.
Most important — and most problematic for the Iranians — is the fact that the United States has a considerable presence near the strait and maintains close situational awareness in the region. Iran does not have the luxury of time when it comes to sowing mines. Some limited, covert mine laying cannot be ruled out, but Tehran cannot exclude the possibility of being caught — and the consequences of being caught would be significant, almost certainly involving a U.S. military strike. In any Iranian attempt to close the strait, it must balance the need to deploy as many mines as possible as quickly as possible with the need to do so surreptitiously. The former attempt could be quickly spotted, while the latter may fail to sow a sufficient number of mines to create the desired effect.
In addition, the damage that even a significant number of mines can physically do may be limited. Most naval mines — especially the older variety — can inflict only minor damage to a modern tanker or warship. During the "Tanker Wars," the Kuwaiti tanker MV Bridgeton and the guided missile frigate USS Samuel B Roberts (FFG 58) were struck by crude Iranian mines in 1987 and 1988, respectively. Though both were damaged, neither sank.
But in mine warfare, the ultimate objective is often psychological. The uncertainty of a threat can instill as much fear as the certainty of it, and Iran need not sow a particularly coherent field of mines to impede traffic through the strait. A single ship striking a naval mine (or even a serious Iranian move to sow mines) could quickly and dramatically drive up global oil prices and maritime insurance rates. This combination is bad enough in the best of times. But the Iranian threat to the Strait of Hormuz could not be more effective than at this moment, with the world just starting to show signs of economic recovery. The shock wave of a spike in energy prices — not to mention the wider threat of a conflagration in the Persian Gulf — could leave the global economy in even worse straits than it was a year ago.
We will not delve here into the calculations of maritime insurers other than to say that, when it comes to supertankers and their cargo, an immense amount of money is at stake — and this cuts both ways. Even damage to a supertanker can quickly run into the millions of dollars — not to mention the opportunity cost of having the ship out of commission. On the other hand, especially at a time when the strait is dangerous and oil prices are through the roof, there would be windfall profits to be made from a successful transit to open waters.
The initial shock to the global economy of a supertanker hitting a mine in the strait would be profound, but its severity and longevity would depend in large part on the extent of the mining, Iran's ability to continue laying mines and the speed of mine-clearing operations. And, as always, it would all hinge on the quality of intelligence. While some military targets — major naval installations, for example — are large, fixed and well known, Iran's mine-laying capability is more dispersed (like its nuclear program). That, along with Iran's armada of small boats along the Persian Gulf coast, suggests it may not be possible to bring Iran's mine-laying efforts to an immediate halt. Barring a cease-fire, limited, low-level mining operations could well continue.
Given the variables involved, it is difficult to describe exactly what a U.S. mine-clearing operation might look like in the strait, although enough is known about the U.S. naval presence in the region and other mine-clearing operations to suggest a rough scenario. The United States keeps four mine countermeasures ships forward deployed in the Persian Gulf. A handful of allied minesweepers are also generally on station, as well as MH-53E Sea Dragon helicopters, which are used in such operations. This available force in the region approaches the size of the mine-clearing squadron employed during Operation Iraqi Freedom to clear the waterway leading to the port of Umm Qasr, although it does not include a mine countermeasures command ship and represents a different clearing scenario.
The clearing of the Strait of Hormuz would begin with the clearing of a "Q-route," a lane calculated to entail less than a 10 percent chance of a mine strike. While there may be considerable uncertainty in this calculation, the route would be used for essential naval traffic and also would play a role in the ongoing clearing operation. The time it would take to clear such a route would vary considerably, based on a wide variety of factors, but it could be a week or more. And a Q-route suitable for large supertankers could take longer to clear than the initial route.
The sooner maritime commerce can resume transiting the strait (perhaps escorted at first by naval vessels), the shorter the crisis would be. The more time that passes without a mine strike, the faster confidence would return. But another mine strike could cause another shock to the global economy, even after clearing operations have been under way for some time.
The fact is, the United States and its allies have the capability to clear naval mines from the Strait of Hormuz, technically speaking. But mine countermeasures work is notoriously under-resourced — it is neither the sexiest nor the most career-enhancing job in the U.S. Navy. So while even a sizable mine-clearing operation in the strait would have historical precedent in other locations, it would be wrong to assume that such an operation would go smoothly and efficiently, even under the best of circumstances.
Ultimately, Iran's military capabilities should not be understood as tools that can only be used independently. If it attempted to close the strait, Iran would draw on the full spectrum of its capabilities in order to be as disruptive as possible. For example, Iran could hold its anti-ship missiles in reserve and launch them at smaller mine countermeasures ships conducting clearing operations in the strait, since these vessels have nowhere near the defensive capabilities of surface combatants. It would also take a considerable amount of time for Washington to send more countermeasures ships to the area from the continental United States above what would likely be deployed ahead of a crisis (if Washington had the luxury of enough warning).
The bottom line is that there is considerable uncertainty and substantial risk for both sides. But while Iran's capability to actually "close" the strait is questionable, there is little doubt that it could quickly wreak havoc on the global economy by doing much less.
