Mines Remain the Weapons that Wait

By Lee M. Hunt

Planners have arrived at a turning point: Antipersonnel land mines are under attack with an intensity not seen since the Russo-Japanese War of 1904-05, and yet mine warfare is poised for a leap in technological innovation and operational utility surpassing anything in its past. What shall be the mine's ultimate fate?

Certainly, those calling for a ban on antipersonnel mines are justified in their concern. The problem that has been with us since two young boys examined one of David Bushnell's keg mines on the banks of the Delaware River in the winter of 1776—and paid for their inquisitiveness with their lives. Unfortunately, we have not prized mines or taken the trouble to understand their unusual value in war as we have other weapons. But we must begin this task if the mine is to remain in the arsenal of weapons, and achieve its full potential.

The sea mine was introduced during the American Revolution and the land mine during the American Civil War. Both are products of American ingenuity. In 1970, absent a fitting definition, the National Academy of Sciences' Mine Advisory Committee defined the mine as a "weapon that waits." As such, mines are to other weapons as trapping is to hunting, and therein lies their strength—the the stigma often associated with them and their vulnerability to criticism.

Sea mines are primarily strategic weapons; their tactical applications trail a distant second. Their use must be integrated thoroughly with overall campaign strategy, and they should be used early and massively in any war for which suited. Their primary purpose is to impede the mobility of an adversary's combat and logistics forces—in effect, turning water into land—to channel those forces into the fields of fire of other weapons; to force the expenditure of resources and manpower; to alter the opponent's strategy and timetable while inducing psychological stress; and finally, to wear down his forces.

Sea mines can be delivered by surface ship, submarine, and aircraft without necessarily placing the delivery platform in danger. In the war in which sea mines played their greatest role and in the theater that kept the best records, the 25,000 U.S. sea mines planted during the World War II campaign in the Pacific sank 1,075 enemy ships and submarines at a cost of 55 allied aircraft, no ships, and no submarines. In that campaign, given the limited assets available caused by the attack on Pearl Harbor, the Europe First strategy, and Japan's dependence on sea power, we would have been well advised to use mines early and massively. Instead, because of a lack of preparation, we did just the opposite.

Unlike other weapons, the mine, once planted and armed, carries out its assigned mission day and night, in all weather, and without human frailties up to the end of its battery life, unless equipped for automatic sterilization. The known record is 25 years (1945-1970 in the home waters of Japan) with, unfortunately in this case, a perfect performance in the end game. From the outset, the mine has been that long-endurance robotic warrior now widely sought in research laboratories.

Sea mines and minefields are difficult to locate beforehand (consider the fate of the USS Princeton [CG-59] and the USS Tripoli [LPH-10] in the Persian Gulf during Operation Desert Shield-Desert Storm). After only a few encounters, the threat grows in an adversary's mind until mines are perceived to be everywhere. According to one account, 90% of all mine countermeasures (MCM) operations have been conducted in waters that held no mines, making MCM one of the most inefficient of military counter operations.

To counter the 700,000 mostly defensive sea mines planted by all sides in World War II, the Germans devoted 1,270 ships and 46,000 men; the Japanese 300 ships and 10,000 men; Britain 1,100 ships and 53,000 men; and the United States 560 ships and 37,000 men. This does not count the combatants used for defense during sweeping operations or the logistics burden imposed. To satisfy the terms of the peace agreement after the Vietnam War, Project End Sweep devoted 87 ships, 132 days, and $20 million to clear a minefield that was no longer there (explosively self-sterilized).6 More recently, Desert Storm Coalition forces used 37 MCM platforms against 2,600 mines.

These figures only hint at the effectiveness of the mine's main strategic objective. It is well documented that the 12,126 sea mines delivered in the home waters of Japan (Operation Starvation) by the Twenty-First Bomber Command during the last six months of World War II, in addition to causing 431 ship casualties and raising MCM to Japan's number one defensive priority, reduced overall shipping to the home islands from 820,000 tons per month to 170,000 tons. Shipping through the narrow Shimonoseki Strait was reduced even more—from 520,000 tons to 9,000 tons. The Japanese considered the 1,529 B-29 minelaying sorties of Operation Starvation (5.7% of the total sorties during the period, with an attrition of less than 1%), which accounted for more ship casualties than all other Army and Navy weapons during the period, to have been more damaging to the war effort than the bombing and incendiary raids of the other 94.3%. Further, many believed that the war would have been brought to a close short of bombing Nagasaki and Hiroshima, had the mining campaign been started earlier in 1945, as some urged.

Operationally, if not technically, the bottom influence mine was the most sophisticated weapon to emerge from World War II. It featured: delivery by surface ships, submarines, and aircraft; targetable against surface ships and submarines; triple target signature sensors singly (or acoustic and magnetic) or in combination; target size discrimination; 200-foot kill distance; shock and bubble pulse damage mechanism; multiple counter-countermeasure capability; one year minimum target search capability.

Although the surviving record is far from adequate, World War II was our most defining experience with the sea mine; 100,547 offensive mines alone accounting for 2,665 ship and submarine casualties. The lessons learned from that experience, however, have not been taken to heart by present planners.

Over the intervening half century, relatively few significant advances in mine design have been made over the proved bottom-influence mine. In the mid-1960s, the thin film magnetometer developed by Burroughs resulted in the Destructor and the follow-on Quickstrike series of mines widely used on both land and sea during the Vietnam War. And, rather than complete development of the highly capable submarine-launched mobile mine (SLMM) brought to the prototype stage in the mid-1960s, the surplus and less capable Mk 37 torpedo was adapted to the purpose. Now our only mobile mine is being deleted from inventory without replacement, as once planned, by the more capable Mk 48 torpedo. Except for several significant mechanism upgrades, our remaining sea mines embody largely 1960s technology.

Other than the quarter million Mk 36 Destructors used both on land and in the highly successful Haiphong mine blockade, the equally successful Nicaraguan harbor blockade (one ship casualty for every two mines planted), and those mines supplied to our allies, we have made little use of sea mines since 1945.

The unanticipated end of the Cold War and the resulting reduction in budgets, force levels, and manpower have left the Navy-Marine Corps team forward deployed in a much less stable world. The mightiest naval capability in history now uses blue water as a transit route to focus that capability against the land. The "Maritime Strategy" has been replaced by "Forward . . . From the Sea" and "Operational Maneuver From the Sea," naval strategies that are reminiscent of the amphibious assaults of World War II, and which call for a belated upgrade in our minewarfare capability.

The combat environment now materializing before us has been described as Network Centric Warfare, in which power rests in the command-and-control network, and the platforms are simply on-command sensor-shooter nodes on the net. In that world, strategy takes an even higher position, the abstraction of combat increases, joint plans and operations become essential, and the net becomes the highest-value target. It is a combat environment in which detailers no longer can afford to urge the best and the brightest to avoid mine warfare duty, and the trapper finally takes his rightful place alongside the hunter—becoming a distinct robotic node on the net, serving in lieu of scarce, expensive sensor-shooter platforms.

The fundamental advances in sea-mine design will come from:

  • Continued miniaturization of computers and solid state electronics
  • New explosive compounds with increased energy yield per unit volume
  • Stealth technology

Miniaturization and improved explosives can produce mines with increased capability that are less than half the length of present day 79-inch-long Mk 55s. In addition, the new mines will be significantly more resistance to an instrument kill from explosive neutralization charges. A converted nuclear-powered ballistic missile submarine (SSBN), with tubes modified for gravity feed, might carry more than 1,000 such mines. Twelve sorties by this SSBN would suffice to deliver the same number of mines that in World War II required 1,529 B-29 sorties—global reach, global power writ large, indeed.

Stealth technology, such as that being pioneered by the Italian Manta and Swedish Rocan mines, or by self-burial, will degrade seriously the present generation of minehunting sonars and force increased reliance on much slower minesweeping techniques.

One of the oldest arguments against the use of mines is that our own forces may need to pass through the mined areas. In an attempt to cure the problem, the debate over remotely controlled minefields has raged for 30 years even as electronic reliability has improved significantly. The argument falls apart when one considers that we have passed confidently through controlled minefields in harbor approaches through two world wars. The only difference is that controllers were hard-wired to the mines then, whereas future operators will be linked acoustically or electromagnetically under a fail-safe system. Modern surveillance mechanisms also would permit minefields to be turned off in the presence of MCM forces, and sensitivity adjusted to attack MCM forces or to maximize effectiveness against specific target classes.

Minefields with distributed sensors offer other advantages. A field of small, rugged, and relatively inexpensive acoustic-magnetic sensors capable of communicating target classification and position data to a centrally or peripherally located multiple-shot kill system using a torpedo, a missile-delivered torpedo, or a missile. A distributed-sensor minefield, similar to the Homine antitank system developed to the prototype stage by the U.S. Army in the early 1970s, would be immune to existing MCM systems, more easily adapted to remote control, and could be neutralized easily at the end of hostilities.

These examples of next-generation sea mines are simply old ideas made more feasible and reliable by modern technology. Other technology-enabled concepts include:

  • Mines that can be triggered by single class of targets or a single target in a class
  • Stealthy pure pressure mines sweepable only with guinea-pig platforms
  • Submarine-launched mines targeted against antisubmarine warfare aircraft
  • Adaptive sensors capable of adjusting to prevailing environmental conditions
  • Stealthy station-keeping or orbiting antisubmarine thermocline mines
  • Long-range mobile mines with map matching for irregular channels and delivery routes, and with reserve power for attacking any target within detection range
  • Mobile mines capable of placing limpet mines on targets in crowded harbors and amphibious staging areas
  • Mines capable of shifting their position into adjoining swept paths
  • Mines capable of timed, fail-safe explosive sterilization

A land or sea mine, once planted and armed, will as readily fire on friend and neutral as foe during its live period. When disarmed and unswept, it still counts as abandoned ordnance. Such is the mine's dark side.

With a few modern exceptions, virtually all weapons from rifle bullets to strategic nuclear missiles are incapable of discrimination once launched, and those failing to detonate or otherwise discarded represent a vastly greater long-term hazard than do mines, because of their greater number expended in war. To give some perspective, 700,000 sea mines were planted during World War II and extensive MCM efforts after the war removed many of those remaining active. By contrast, Operation Thunderclap, consisting of three U.S. Army Air Force and Royal Air Force bomber waves, dropped 650,000 incendiary bombs on Dresden, Germany, in a single night—13 February 1945. By the end of the Pacific Campaign we were dropping the explosive equivalent of 65,000 Mk 6 mines on Japanese cities every 24 hours. The roughly two-hour bombardment of the Okinawa invasion beaches in the early morning hours of 1 April 1945 consisted of 44,825 5- to 16-inch projectiles, 33,000 assault rockets, and 22,500 mortar rounds. The unknown number of 3-inch, 40mm, and 20-mm explosive projectiles probably exceeded the combined total of all the rest. A 5% dud rate would have left more than 10,000 unexploded rounds from a two-hour portion of a six-year war.

Some dud ordnance fails in such a way that detonation can be caused by even casual disturbance: fortunately, most require rougher treatment. The survival time of abandoned explosive charges in the environment is far longer than we once thought, however. The powder charges in some cannon balls recovered from the mud around Fort Sumter, South Carolina, remain active after 137 years. Thus, the problem is cumulative.

The continuing peacetime casualties from land mines, particularly antipersonnel land mines, have been documented in recent years. Less well documented have been the peacetime ship casualties (loss of life minimal) to live mines. A culling of Lloyds of London records indicates that between the end of World War II and 1974, 519 ships were sunk or damaged by "abandoned explosive ordnance, and that the number may now stand at around 600. Some of these losses were caused by ordnance other than mines (a torpedo, unknown ordnance pulled into a dredger pump room, etc.), but the percentage of casualties caused by live mines is unknown. Figure 1, however, indicates that a significant percentage of those ship casualties in the years immediately following 1945 were caused by live mines. That the number is not higher is a result of adherence to Articles 1, 3 and 5 of the Hague Convention of 1907—which in turn was a direct result of the Russo-Japanese War. (Similar international rules were issued for land mines in 1981 by the United Nations Convention on Prohibitions or Restrictions on the Use of Certain Conventional Weapons Which May be Deemed to be Excessively Injurious or to Have Indiscriminate Effects.

The degree to which the major powers have adhered to the 1907 Convention's dictates on sea mines is encouraging. By World War I, moored mines were being equipped with hydrostatic switches and exploder plugs to sink any mine rising above its preset depth. By World War II and the introduction of the bottom-influence mine, sterilization clocks were installed to drain the mine's batteries or interrupt its firing circuit after a preset interval, and later to detonate the mine's main charge. A classic example of the effectiveness of the Hague Convention was the Haiphong Mine Blockade in which 11,500 sea mines, equipped for timed explosive sterilization, were laid in several phases, and yet the Project End Sweep clearance operation swept but a single mine, and that of dubious origin.

Banning of mines, presently being suggested for antipersonnel land mines, is not a viable solution. The unrealistic belief that banning will deny the use of mines in war ignores the production of relatively sophisticated pressure-activated river and canal mines from battlefield debris and condoms (pressure diaphragm) in jungle workshops by the Viet Cong. Banning simply removes the safest and most reliable mines from world arsenals (as did Senator Patrick Leahy's [D-VT] moratorium on the sale of U.S. land mines), and places dangerous and unreliable mines, without sterilization features, in the hands of rogue nations and paramilitary groups. Further, the definition of what constitutes a mine is so broad as to invite circumvention. Finally, banning denies to our military a weapon whose potential for wartime effectiveness with minimum human fatalities exceeds that of any other weapon now in our inventory.

Needed is a new international convention to modernize and broaden the rules governing the design and use of all sea and land mines. Central to the objectives of that convention should be the requirement that all future mines be equipped with a fail-safe explosive sterilization feature. By fail-safe is meant that a highly reliable sterilization feature be made an integral part of the mine's sensing and firing mechanisms such that to remove it is to render the mine inoperative, and, on arming, the sterilization timing device automatically assumes the minimum setting if the miner forgets or elects not to choose a setting. And importantly, sterilization is only by detonating the mine's main charge. A mine simply rendered inoperative looks like a mine, and must be treated as such, with all that implies, by both MCM forces, deminers and civilians alike. So equipped, the mine serves as a role model for all weapons now adding to that far greater and continually growing problem of abandoned explosive ordnance.

The stigma that once shadowed the mine began to fade with the introduction of the modern concept of total war during Sherman's march through the piney woods of Georgia, and is being rapidly eradicated by the growing abstraction of armed conflict, the desire for maximum effect with minimum casualties, and the need to conserve and leverage diminished platforms in an undiminished world. The mine's underplayed but spectacular role in the major conflicts of this century, largely lost in the well-justified glamour of the dolphin's smile, white scarves streaming in the wind, and the rolling thunder of big naval guns, shows it coming to maturity in the Network-Centric Warfare of the next century. To prepare the mine for that mature role, the gap that has been allowed to grow between technology and mine design must be closed. But with that closing, the mine's Dark Side must be dealt with by modernizing, expanding, and rigorously enforcing the international rules laid down nine decades ago.

Mr. Hunt , now retired and a private consultant, served on the Committee on Undersea Warfare and was the Director of the Naval Studies Board. He wrote “In Stride,” published in Proceedings April 1994. This paper is an updated and shortened version of a paper co-authored with David R. Heebner, Chairman of the Naval Studies Board of the National Academy of Sciences appearing in the proceedings of the International Military Conference held in Abu Dhabi in March 1997.

 

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