August 19, 2026:
In order to make American submarines more effective, the American Navy is working on developing Seabed Superiority. Current operations in the Baltic Sea and the North Atlantic trade routes. This depends on having a sensor network on the seabed, something similar to the Cold War-era SOSUS
This year, China operates 64 well-equipped oceanographic research vessels, most of which were built in the past 15 years. This modern fleet is larger than the combined fleets of the U.S. Academic Research Fleet, the National Oceanic and Atmospheric Administration’s research fleet, and the U.S. Navy’s oceanographic survey vessels. China’s fleet includes polar-capable ships, fisheries research vessels, and ships designed for autonomous unmanned vehicle, remotely operated vehicle, or manned submersible deployments. A technological showpiece is the Zhu Hai Yun, which operates as a mothership for more than 50 unmanned vehicles, including aerial drones, autonomous surface vehicles, and underwater gliders. Its unmanned vessels can operate simultaneously, providing persistent surveillance of an area extending 160 kilometers across, 4 km above the surface, and 1.5 km below the surface while the mothership remains underway.
China has developed five XLUUVs (Extra-Large Unmanned Underwater Vehicles) measuring 15 to 20 meters long. These vehicles can sense physical data, map the seafloor, and carry torpedoes or mines. The XXLUUVs are large enough to carry towed-array sonars and voyage across the Pacific.
For persistent surveillance throughout the water column, China’s Haiyan and Haiyi gliders can operate for months, travel thousands of miles, and periodically transmit their locations and observations of temperature, salinity, and depth via satellite. The US has long used its equivalents, some of which China has obtained because so many have washed up on stray Pacific beaches after accidents. A military variant of the Haiyan glider is equipped with vector acoustic sensors that can determine a bearing line to a sound source, as well as magnetometers for submarine detection.
On the seafloor along the First Island Chain, China’s cabled seafloor observatory, the National Seafloor Scientific Observation Network, serves the dual purposes of environmental research and acoustic monitoring of marine traffic. The East China Sea segment is focused on the shallow continental shelf, while the South China Sea segment reaches depths of 3,000 meters. The network consists of acoustic arrays, seismometers, physical and chemical sensors, and navigation beacons that provide docking and acoustic navigation for underwater drones. Because acoustic arrays and gliders can serve as tripwires for submarine detection, the network is viewed as an underwater Great Wall of China.
To improve ocean and acoustic forecasting, global and regional ocean models assimilate data from ships, satellites, unmanned vehicles, and moored sensors to initialize them more accurately. In 2025, China achieved a major breakthrough in ocean modeling with the LICOM K++ model, which provides 1-km horizontal resolution for three-dimensional, global ocean simulations. This is significantly better than the US models, which simulate global conditions with only 4-km to 9-km resolution. LICOM K++ can simulate fine-scale processes such as oceanic internal waves and microscale eddies—processes that operational U.S. global models must approximate mathematically.
With sustained funding and a blurred line between civilian research and military applications, China has closed the gap in a domain in which the United States has long held a significant advantage: stealthy naval operations. By the end of its current Five-Year Plan, China may achieve parity with U.S. naval capabilities in the western Pacific.
Thirteen years ago, China began installing underwater passive sonar systems in its coastal sea areas. This enabled China to monitor submarines operating off its coasts and, presumably, in the South China Sea. South Korea did the same when it announced it was installing underwater submarine sensors off its coasts, and apparently completed this in 2013. The South Korean effort was in response to North Korea using a small submarine to torpedo a South Korean patrol ship in 2010. China simply wants to keep foreign warships as far away as possible, even if it means trying to force them out of international waters.
China and South Korea did not reveal technical details, but this sort of system is similar to the passive sonar system the United States deployed on the seabed in key areas during the Cold War. SOSUS (Sound Surveillance System) consisted of several different networks. The CAESAR network covered the continental shelf areas bordering the North Atlantic. In the North Pacific, there was COLOSSUS plus a few sensors in the Indian Ocean and a few other places that no one would talk about. The underwater passive sonars listened to everything and sent their data via cable to land stations. From there it was sent back to a central processing facility, often via satellite link. SOSUS was accurate enough to locate a submarine within a circle no wider than 100 kilometers. That's a large area, but depending on the quality of the contact, the circle could be reduced to as little as ten kilometers. The major drawback was that it did not cover deep-water areas beyond 500 kilometers from the continental shelf edge. This is not a problem for the South Korean or Chinese systems, as both cover only coastal waters or shallow offshore areas, such as the South China Sea.
SOSUS systems are very expensive to maintain. SOSUS survived the end of the Cold War by making its sensors available for civilian research and adopting cheaper, more powerful electronic and communications technology. While many parts of the SOSUS have been shut down, additional portable SOSUS gear has been put into service and deployed as needed.
South Korea benefited from U.S. help with SOSUS and in collecting and processing submarine sound signatures in the area. The U.S. also helped South Korea obtain more sensitive passive sonar systems that can locate submarines more accurately. The U.S. has been conducting research in this area and knows that such cooperation would provide American access to the South Korean SOSUS. South Korea also has the design and manufacturing capability for this sort of device. The first South Korean SOSUS system was placed off the west coast, near the North Korean border. North Korean submarines, traveling underwater, using battery power and near the coast, are very hard to detect. The South Korean SOSUS will help even the odds. China’s Internet-based espionage efforts have probably already stolen a lot of American SOSUS secrets, and that helped a lot.
If there were a war with China, one of the main goals would be to disrupt Chinese shipping with submarines, especially the quiet and heavily armed Virginia nuclear-powered submarines that operate in the Pacific. As China became a potential threat, the Pacific Fleet received more Virginia-class submarines. The Virginias were there to shut down Chinese trade on short notice by deploying hundreds or thousands of naval mines near Chinese ports. Their primary weapon will be naval mines. China’s mine-clearing capability is believed to be limited.
Since the end of the Cold War, a growing number of American naval officers and civilian experts have urged greater attention to naval mines. The United States was not alone, and in 2012, it led the U.S. and over 30 other nations in a joint mine-clearing exercise called the International Mine Countermeasures Exercise 2012. These training events aimed to counter Iranian attempts to block access to the Persian Gulf through the Strait of Hormuz. 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 have large 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 has 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. The Persian Gulf is a busy waterway. It is 989 kilometers long, and the average depth is 50 meters. Naval mines are Iran's best bet for shutting down the straits. Iran's problem is that it has a small navy, an obsolete air force, and a poor track record of 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 to cut off each other's oil sales. Iran didn't want to completely shut the Straits of Hormuz because that would have stopped its own oil revenue, only to impede it to force the United States to make Iraq stop its attack on Iran’s own exports. Over 500 ships were attacked, 61 percent of them tankers. Only 23 percent of the tankers attacked 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. 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 a 30-kilometer-wide deep channel. Normally, ships stick to narrow channels, going in and out to avoid collisions. The main Iranian threat has always been seen as the use of naval mines. The Arab states have more mine-clearing equipment and larger air and naval forces than Iran. In addition, the United States and NATO forces are in the area. The problem was that none of these mine-clearing forces had ever practiced under 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, during subsequent mine-clearing exercises and since the US attacked Iran in March 2026.
For an Iranian attempt to mine to succeed, it would have to place mines at the bottom of the straits and then prevent the rest of the world from clearing them. That would be difficult, as would 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, which is a small arsenal compared to Russia, China, and North Korea. Most agree that these mines pose a serious danger. While often ignored, naval mines are a formidable weapon. But these passive weapons don't get the respect they deserve. The historical record indicates otherwise.
Modern naval mines were first widely used over a century ago, during the 1904-1905 Russo-Japanese War. 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 as defensive barriers against enemy movement in the North Sea. They also used mines offensively, secretly placing them across known enemy sea routes. More than 1,000 merchant ships and warships 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 even more mines. During World War II, a total of 2,665 ships were lost or damaged by 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. 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. Some 670 ships were hit, with 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 lasted 45 months, from December 1941 to August 1945. Some 4.8 million tons of enemy shipping were 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 or torpedo-armed submarines, 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 suggests that mines may have been more effective than torpedoes, even when 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, sinking or damaging 11 ships. This was a ratio of 29 mines used for each ship hit. More importantly, eight major ports were closed for 40 days. One port, Charleston, South Carolina, was closed for 16 days, tying up not only merchant shipping but also the thousands of men, warships, and aircraft involved.
American submarines also waged a limited mine campaign in the Pacific. For 658 mines used, 54 ships were sunk or damaged at a cost of 12 mines per ship. No subs were lost. Japan tied up considerable resources 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 laid 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. They used them to defend Wonson harbor. It took several weeks for UN forces to clear these, at the cost of a dozen ships being hit. Half of these ships were destroyed.
During the Vietnam War, over 300,000 American naval mines were used, primarily in rivers. Most were not built as mines but as aerial bombs equipped with magnetic sensors instead of fuzes. These bombs/mines used a small parachute to ensure they landed without damage. In shallow water, these makeshift weapons sat on the bottom and performed like mines. Haiphong Harbor was actually mined with 11,000 of these destructors, as the US Air Force called them. Haiphong Harbor was completely shut down for months, and it took years to clear all the American mines. The destructor mine design was so successful that it is still in use, using more modern electronics, such 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 a helicopter carrier and cruiser were 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. After the fighting stopped, it took over a month of mine clearing 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 once again surprise everyone with their effectiveness. 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 improve its 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 that sit on the seabed. These UUVs were deployed in the Persian Gulf to address Iran's potential use of naval mines. The Seafox UUVs are already deployed on Avenger mine-hunting ships in the Persian Gulf.
SeaFox is a small, battery-powered sub measuring 1.4 x 0.4 x 0.2 meters, weighing 43 kg, and connected to a surface ship or hovering helicopter by a fiber-optic cable. There, the controller can move the SeaFox close to a suspected mine using a small sonar unit, then turn on a spotlight for a video camera to examine the object and determine if it is a mine. If it is, SeaFox gets closer and detonates a shaped charge explosive, 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.
The only American minesweepers are the four of the 13 Avengers still in service. These 72.3-meter-long ships draw only 4.8 meters of water, allowing them to operate close to shore. The crews are trained to navigate such shallow areas. The Avengers are armed with two 12.7mm machine guns, two 7.62mm machine guns, two 40mm automatic grenade launchers, and have a crew of 84. In 2012, Avengers operated in the Persian Gulf from Bahrain. Others were based in Sasebo, Japan. Some were based at San Diego, California.
The U.S. Navy needs these minesweepers because replacements in the form of more 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 its ability to detect mines on seafloors cluttered with natural or man-made objects. 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.
As of 2024, the Navy has no active minesweeper ships. Some of the LCS ships are supposed to be capable of mine sweeping, but it is unclear if they are actually ready for service
The Navy also had a dozen smaller Osprey-class coastal mine hunters (900 tons displacement, crew of 51), but it gave them to foreign navies, and the LCS and new minesweeping helicopters are to replace them.
The Navy has also equipped helicopters for mine clearing, but is having a very difficult time maintaining its force of 30 MH-53E helicopters. These aircraft are the only ones that can tow a sled carrying naval mine-detecting gear. This is called AMCM/Airborne Mine Countermeasures and is considered essential in areas like the Persian Gulf, where Iran might deploy many naval mines that would need 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. Replacements with lighter sleds that smaller, more modern helicopters could pull did not work out as expected. So retirement was pushed to 2012, then to 2017, and the Navy currently hopes to keep some MH-53Es operational until 2030.
Meanwhile, efforts continue to develop lighter mine-hunting equipment. Some of these projects have had limited success. The AQS-24A mine-hunting system looks like a torpedo with extra fins and attachments. 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 detects mines lying on the seabed, waiting for ships to pass over them. The bottom mine then detonates if it detects the type of ship it was programmed to attack. The U.S. Navy has been using this mine-hunting approach since the 1980s. The original sled system underwent several major upgrades and is considered highly reliable and effective. The MH-53E sled can still 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 low-flying, smaller helicopters. Surface mines are either moored or floating, and many float just below the surface. The laser operates very quickly, enabling the ALMDS-equipped helicopter to survey 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 new U.S. equipment uses foreign tech. While new mine designs have become more effective, the basic problem remains: many older designs are still very dangerous, especially for the unprepared.