Ever since the end of the Cold War a growing number of American naval officers and civilian experts have been urging that more attention be paid to dealing with naval mines. The United States was not alone and in 2012 that led to the U.S. and over 30 other nations conducting a joint mine clearing exercise, called the International Mine Countermeasures Exercise 2012 (September 16-27). The numerous training events were directed at dealing with Iranian attempts to block the entrance (Straits of Hormuz) to the Persian Gulf. The impact of that exercise led to another being held annually ever since. While Iran is the most immediate user of naval mines, it is not alone. North Korea, China and Russia much larger naval mine stockpiles, but these three are not boasting of how and when they would use them,
Iran insists that because of its mines and other weapons it will have no trouble blocking the export of oil via the Straits of Hormuz. Some 35 percent of the world's oil shipments pass through these straits, which comes to about 15-20 tankers a day (plus a dozen or more non-tankers). The Persian Gulf, in general, is a busy waterway. It is 989 kilometers long and the average depth is 50 meters (maximum depth is 90 meters). Naval mines are Iran's best bet if they want to shut down the straits. The Iranian problem is that they have a small navy, an obsolete air force, and a poor track record when it comes to shutting down tanker traffic in the Persian Gulf or the Straits of Hormuz. They tried once before, in the 1980s, when they were at war with Iraq. The two nations began attacking each other's tanker traffic early on, in an attempt to cut off each other's oil sales (and, thus, military purchases). Iran didn't want to shut the Straits of Hormuz because it needed the oil revenue more than Iraq (which was getting billions in aid from other Arab states) did. So each country concentrated on attacking shipping in the Persian Gulf. Over 500 ships were attacked, 61 percent of them tankers. Only 23 percent of the tankers attacked (mainly with anti-ship missiles) were sunk or immobilized. The attacks, using fighter-bombers and warships, only hit about two percent of the ship traffic in the Gulf. Iran lowered its oil prices to cover the higher cost of ship insurance and, in 1986, Russia and the United States intervened to protect Kuwaiti and Iraqi tankers (which were taking most of the damage).
The Iranian military is in worse shape today than it was in the 1980s and would not last long trying to attack ships. That leaves the Straits of Hormuz. This is actually a wide (about 30 kilometers) deep channel. Normally, shipping sticks to narrow (a few kilometers wide) channels, going in and out, to avoid collisions. The main Iranian threat has always been seen as naval mines. The Arab states have a lot of mine clearing equipment and more numerous air and naval forces than Iran. In addition, there are the United States and NATO forces in the area. The problem was that all these mine clearing forces had never practiced under realistic (wartime) conditions. In short it has long been unclear exactly what it would take to deal with Iranian mines in the straits. Many of those questions were finally answered in 2012 and during subsequent mine clearing exercises.
For an Iranian mining attempt to work they would have to get the mines onto the bottom of the straits and then prevent the rest of the world from clearing those mines. That would be difficult, as will Iranian attempts to plant additional mines. Such attempts would not be impossible as Iran has small submarines and speed boats along with sailors willing to carry out suicidal missions to deliver the mines. Even that may not be sufficient, as this sort of fanaticism failed against the Americans in the 1980s. While Iran has worked to overcome their shortcomings, most of the solutions appear to be publicity stunts mainly meant to make the Iranian population feel better.
Iran has a few thousand naval mines and that is a small arsenal compared to Russia (over 200,000), China (over 100,000) and North Korea (over 50,000). It is generally agreed that all these mines are a serious danger. While often ignored, naval mines are a formidable weapon. But these passive weapons just don't get any respect. The historical record indicates otherwise.
Modern naval mines were widely used for the first time over a century ago, during the Russo-Japanese war (1904- 1905). These were contact mines, floating in shallow water and kept in place with an anchor and chain. When the tide was right they would be just below the surface, ready to explode whenever struck by a ship. Some 2,000 of these mines were used to destroy sixteen ships during the Russo-Japanese war. That's one ship lost for every 125 mines used.
During World War I (1914-18), modern mine tactics and clearing methods evolved. Thousands of mines were laid to provide defensive barriers against enemy movement in the North Sea. Mines were also used offensively by secretly placing them across known enemy sea routes. More than 1,000 merchant and war ships were lost because of the 230,000 mines used. That's over 200 mines used for every ship lost.
During World War II there was a major effort to develop better mine clearing methods to deal with an even larger number of mines. During World War II a total of 2,665 ships were lost or damaged to 100,000 offensive mines. That's one ship for every 37 mines. Some 208,000 mines were used defensively to inhibit enemy movement and tie up his resources.
Naval mines achieved several striking successes during World War II. In the Pacific naval mines proved more destructive to the Japanese war effort than the atom bombs. During a 10 week period between April and August 1945, 12,000 mines were delivered to the Japanese coast by American bombers. These destroyed 1,250,000 tons of Japanese shipping (670 ships hit, 431 destroyed). That's 18 mines for each ship hit. The Americans had air superiority, so losses during these 1,500 missions amounted to only 15 planes, most of them accidents. Had these missions been flown against opposition, losses would have been between 30 and 60 aircraft, plus similar losses to their fighter escorts. Either way it was a stunning success for naval mines,
A conventional submarine campaign was also waged against Japanese shipping using mines. Comparisons between subs using mines and torpedoes are interesting. A hundred submarines were involved in a campaign that ran for 45 months from December, 1941 to August, 1945. Some 4.8 million tons of enemy shipping was sunk with torpedoes. For every US submarine sailor lost using submarine launched torpedoes, 560 tons of enemy ships were sunk. During the mine campaign 3,500 tons were sunk for each U.S. fatality. On a cost basis the difference was equally stark. Counting the cost of lost mine laying aircraft (B- 29's at $500,000 each) or torpedo armed submarine ($5 million each), we find that each ton of sunk shipping cost six dollars when using mines and fifty-five dollars when using submarines. This data was classified as secret until the 1970s. It indicates that mines might have been more effective than torpedoes, even if the mines were delivered by submarine.
The Germans waged a minelaying campaign off the east coast of the United States between 1942 and 1944. Only 317 mines were used, which sank or damaged 11 ships. This was a ratio of 29 mines used for each ship hit. More importantly eight major ports were closed for a total of 40 days. One port, Charleston, South Carolina, was closed for 16 days, tying up not only merchant shipping but the thousands of men, warships, and aircraft dealing with the situation. American submarines also waged a limited mine campaign in the Pacific. For 658 mines used, 54 ships were sunk or damaged (12 mines per ship). No subs were lost. Considerable Japanese resources were tied up dealing with the mines. On the Palau atoll the port was closed by the mines and not reopened until the war ended. Even surface ships were used to lay mines. Three thousand mines were laid by destroyers. Only 12 ships were hit but these were barrier fields, not the ambush type mine fields that a submarine can create by sneaking into an enemy held area.
In Korea during the early 1950s, the Soviets provided North Korea with 3,000 mines, many of 1904 vintage. These were used to defend Wonson harbor. It took several weeks for UN forces to clear these, at a loss of a dozen ships hit. Half of these ships were destroyed.
During the Vietnam War over 300,000 American naval mines were used, primarily in rivers. The vast majority were not built as mines but were aerial bombs equipped with magnetic sensors instead of fuzes. These bombs/mines used a small parachute to insure that no damage occurred on landing. In shallow water these makeshift weapons sat on the bottom and performed as well as mines. Haiphong Harbor was actually mined with 11,000 of these "destructors," as the US air force called them, and less than a hundred conventional mines. Haiphong Harbor was shut down completely for months, and it took years to clear out all the American mines. The "destructor" mine design was so successful that it is still in use, using more modern electronics, as the Mk 62 mine.
During the 1991 Gulf War the Iraqis laid over a thousand mines off the Iraqi and Kuwaiti coast. The predominantly US naval forces did not have sufficient mine sweeping resources to deal with this situation and had a helicopter carrier and cruiser hit and damaged while trying to clear the area. This effectively prevented any US amphibious operations, although the Marines were not going to be used for a landing anyway. It took over a month of mine clearing after the fighting ceased to eliminate all the mines. In the meantime, two U.S. warships were damaged by these mines. In 2003, the Iraqis again tried to use mines, but were hampered by prompt American, British, and Kuwaiti action.
In any future war naval mines will again surprise everyone with how effective they are. It is feared that terrorists might get their hands on some bottom mines, but so far, there do not appear to have been any attempts.
Meanwhile the 2012 international mine clearing exercise prompted the United States to made several moves to improve mine clearing capability. The U.S. Navy ordered several dozen more of the expendable SeaFox UUVs (unmanned underwater vehicles). These are used to destroy bottom mines (which sit on the seabed). These UUVs were sent to the Persian Gulf to deal with potential Iranian use of naval miles. The Seafox UUVs are used on Avenger mine hunting ships already in the Persian Gulf.
SeaFox is a small (1.4x.4x.2 meters/55x16x8 inches) battery powered sub that weighs 43 kg (95 pounds) and has a fiber-optic cable connecting it to a surface ship or hovering helicopter. There the controller can move the SeaFox close to a suspected mine (using a small sonar unit to assist navigation), then turn on a spotlight for a video cam to examine the object and determine if it is a mine. If it is SeaFox gets closer and detonates a shaped charge explosive, sending a shaft of hot plasma through the mine destroying itself and the mine. SeaFox has an endurance of about 100 minutes, a top speed of 10 kilometers an hour, and can dive as deep as 300 meters (930 feet).
The only American minesweeper ships are the 13 Avengers. These are 72.3 meter (224 foot) long ships that draw only 4.8 meters (15 feet) of water, enabling them to operate close to shore. The crews are supposed to be trained in navigating such shallow areas. The Avengers are armed with two .50 cal. (12.7mm) machine guns, two 7.62mm machine guns, two 40mm automatic grenade launchers, and have a crew of 84. In 2012 four Avengers were in the Persian Gulf, operating out of Bahrain. Another three were based in Sasebo, Japan. The other six are based at San Diego, California.
The U.S. Navy needs these minesweepers because replacements (minesweeping helicopters and minesweeping versions of the new LCS ship) have been delayed by technical problems. Meanwhile the U.S. has upgraded the sonars on its Avenger class ships. The new AN/SQQ-32(V)4 mine hunting sonar improves the ability of the sonar to spot mines on sea bottoms cluttered with other stuff (natural or manmade). In many parts of the world shallow coastal waters are used as a dumping ground for junk that won’t float ashore. This has been found to help hide bottom mines. The Avengers have also received new engines. The four original diesel engines in each Avenger have never been very reliable. With their new engines the Avengers can still move at up to 27 kilometers an hour. Normally, however, the Avengers move much more slowly (3-4 kilometers an hour) when searching for mines. The Avengers also received improved hydraulics and new mine destruction systems.
The upgrade is part of an attempt to deal with delays in the arrival of the LCS class ships, or at least the ones equipped for mine hunting. So for the last decade the navy has been hustling to refurbish its existing Avengers. The 3,000 ton LCS ships are designed for minesweeping (and a lot of other jobs) but the 1,400 ton Avengers specialize in minesweeping. Built mostly of wood and very little iron, the fourteen Avengers entered the fleet between 1987 and 1994, and all are still in service. The upgrades will enable the surviving Avengers to remain in service at least until 2016 and probably until the end of the decade.
The navy also had a dozen smaller Osprey class coastal mine hunters (900 tons displacement, crew of 51), but these were all given away to foreign navies and are to be replaced by the LCS and new minesweeping helicopters.
The navy has also equipped helicopters for mine clearing. But the navy is having a very difficult time maintaining its force of 30 MH-53E helicopters. This aircraft are the only ones that can tow a sled containing naval mine detecting gear. This sort of thing is called AMCM (Airborne Mine Countermeasures) and is considered essential in areas, like the Persian Gulf, where the enemy (Iran) might use a lot of naval mines that would have to be cleared quickly in wartime.
The MH-53E is an update of the original 1960s era CH-53 and entered service in the early 1980s. Fifty MH-53Es were built and they have been worked hard ever since. That’s why only 30 are left and few of them are fit to fly at any one time. Originally the navy planned to retire the MH-53Es in 2008, but replacements (lighter sleds that could be pulled by smaller and more modern helicopters) did not work out as expected. So retirement was pushed to 2012, then 2017 and currently the navy hopes to keep some MH-53Es operational into the 2020s.
Meanwhile efforts continue to develop lighter equipment for the mine hunting task. Some of these projects have had limited success. The AQS-24A mine-hunting system looks like a torpedo with extra fins and attachment. It is lowered into the water and dragged by the helicopter at speeds of up to 34 kilometers an hour. The AQS-24A contains a high resolution sonar that seeks out mines than lay on the sea bottom, waiting for ships to pass over. The bottom mine then detonates if a ship type it was programmed to attack is detected. The U.S. Navy has been using this mine hunting approach since the 1980s. The original sled system went through several major upgrades and is considered very reliable and effective. The MH-53E sled is still able to carry more equipment and sweep a larger area faster.
The U.S. Navy has also developed a complementary system, ALMDS (Airborne Laser Mine Detection System). Designed to operate from the MH-60S helicopter, ALMDS uses a Laser Imaging Detection and Ranging blue-green laser to detect, and identify naval mines near the surface. Unlike the AQS-24A, ALMDS operates from the low flying, and smaller, helicopters. Surface mines are either moored (via a chain to the bottom) or floating (a favorite terrorist tactic), and many float just below the surface. The laser works very quickly, and enables the ALMDS equipped helicopter to quickly check out large areas for surface mines. Terrorists have used naval mines before, of the floating variety. Navies tend to use the more sophisticated, expensive and hard-to-get bottom mines (that lie on the bottom, in shallow water).
American allies have also developed new mine detection and clearing tools and some of the new U.S. equipment uses foreign tech. While new mine designs have become more effective, the basic problem is that the many older mine designs are still very dangerous, especially for the unprepared.