Twenty-First-Century Aerial Mining

Note: This article is an excerpt of the external pageoriginal full articlecall_made, which was published in the March-April issue of the external pageAir and Space Power Journalcall_made.

On 23 September 2014, a B-52H bomber at high altitude north of Guam accomplished an aviation first—the release of a winged, precision aerial mine (fig. 1). The inert, orange and white GBU-62B(v-1)/B Quickstrike-ER (extended range) separated cleanly from the B-52, rolled, and three seconds after release, the BSU-104 wings deployed, transforming a free-fall munition into a medium-range weapon. Under command from the attached Joint Direct Attack Munition (JDAM) tail kit, the weapon flew around 40 nautical miles (nm) and impacted the water. Had the weapon been a live system dropped in shallow water, it would have settled to the bottom to lie in wait for a target. This effort marked the first advance in aerial mine-delivery techniques since 1943 and demonstrated a capability that substantially changes the potential of aerial mining in a threat environment. Using off-the-shelf components and operational aircraft, aerial mining quietly entered the twenty-first century.

Historical Background

The use of mines in naval warfare is extensive, dating from the American Civil War.1

The Luftwaffe mined the Thames Estuary in November 1939, marking the first use of aerial mines. By 1940 the Royal Air Force (RAF) was laying an average of 1,000 each month for the entire duration of the war. For some areas, such as inland waterways and the Danube, mine laying by aircraft was the only option.2

Aerial mines, placed in the harbor approaches and training areas used by U-boats, sank 16 of the 26 German submarines destroyed by mines during the entire war.3

The US Navy’s offensive mine laying began in late 1942, when the USS Thresher mined the Gulf of Siam. In December Trigger laid mines near Tokyo and witnessed the first sinking before leaving visual range. Nevertheless, the number of submarine-laid mines was small, and risk to the boats was high. Avenger torpedo bombers laid mines effectively against Japanese island bases in conjunction with antishipping strikes, but no such attempt took place against the home islands. In total, naval aviation was responsible for only 3 percent of the aerial mines laid in the Pacific.4

Fifth Air Force relied on the RAF and Royal Australian Air Force (RAAF) for its mine-laying capabilities.5 Tenth Air Force, though, embraced aerial mining more enthusiastically and closed the Rangoon River for the duration by using British mines from early 1943. Fourteenth Air Force laid airlifted mines in China’s rivers, including the Yangtze. Twentieth Air Force conducted its first aerial mine-laying mission off Sumatra in August 1944, later mining Singapore, Saigon, and Cam Ranh Bay.6

In March 1945, the 313th Bombardment Wing (B-29) began mine-laying operations in Japanese home waters.7 Referred to as “Starvation” missions, the mining effort was directed at the Shimonoseki Strait, the key remaining choke point in the Japanese maritime supply network, along with Tokyo, Nagoya, and smaller Japanese and Korean ports.8 Despite the short duration, aerial mining effectively stopped maritime traffic, racked up almost as many ships damaged as all US Army Air Forces (USAAF) land-based air during the entire war, and accounted for half of all of the ships sunk or damaged during the aerial mining period. According to Wesley Frank Craven and James Lee Cate,

The 313th Wing got into the game late, operating with mines for only four and one-half months and at a period when the enemy’s merchant fleet had contracted in size and in scope of its activities. During that short period, mines planted by the wing were more destructive than any other weapon, accounting for about half of the total tonnage disposed of. To accomplish this task, the 313th sent out 1,528 sorties and planted 12,053 mines, a much heavier effort than had been suggested by the Navy in the negotiations of 1944 and, indeed, the heaviest aerial mining campaign ever waged.9

The United States again conducted large-scale aerial-mining efforts in Vietnam. President Johnson authorized mining of the Song Ca, Giang Song Ma, Kien, and Cua Sot Rivers in 1967.10 Throughout the later days of Operation Rolling Thunder, carrier aircraft were mining inland roads and waterways.11

Aircraft from the Coral Sea mined Haiphong Harbor on 8 May 1972, dropping 36 Mk-52 mines and giving the harbor the dubious distinction of being the only foreign port mined by the United States in two wars.12 The mining of Hon Gai and Cam Pha followed, along with the approaches to Haiphong. All were periodically reseeded. The mines shut down Haiphong until Operation End Sweep in 1973, which cleared Vietnamese harbors (but not rivers).

Aerial mining remained a Cold War mission conducted by US Air Force bombers and carrier air, primarily with the intention of constraining the Soviet fleet—especially submarines. Two days into Operation Desert Storm, A-6 aircraft from the USS Ranger dropped 42 mines in the Khawr Az Zubayr River to no known effect, marking the most recent combat drop of aerial mines.13 With the exception of this sortie, which resulted in the loss of Jackal 404 and its crew, aerial mining has proven highly effective in enforcing a maritime blockade against both warships and submarines.

The Mines

In Operation Starvation, the B-29s employed Mk-25 (2,000-pound) and Mk-26/36 (1,000-pound) aerial mines. Blunt-nosed and parachute-retarded, these weapons had magnetic fuzes with either pressure or acoustic sensors, variable sensitivity settings, randomly set arming delays, and ship counters between one and nine, allowing some mines to ignore a certain number of ships before they triggered. None had any kind of deactivation device, and all were bottom mines.14

Mines used in Vietnam were mostly variations of general-purpose (GP) bombs with high drag tails. Called Destructors, the Mk-36 (500 pounds), Mk-40 (1,000 pounds), and Mk-41 (2,000 pounds) incorporated arming delay and self-destruct features. Fuzes were magnetic, seismic, contact, or a combination, and the system could be used on land or in shallow water. Destructor mines and GP bombs differ only in fuzing and (sometimes) in the tail kit attached to the bomb body. This design feature continued in the Quickstrike, the successor to the Destructor series.

The Quickstrikes (Mk-62/-63/-64/-65) are the current US air-delivered bottom mines, intended for shallow water at depths from 40 to 200 feet.15 The weapon consists of a GP bomb body, safe/arming device, tail kit, battery, adapters, and a target detection device (TDD). The Mk-65 is the only weapon in the series not derived from a GP bomb. The legacy Mk-57 TDD is magnetic-seismic, and the Mk-58 is magnetic-seismic-acoustic. The newest TDD, intended to replace both of the older TDDs, is the microprocessor-driven, programmable Mk-71.

Mine Delivery

Typically, mine delivery has been a low-altitude operation, largely because of the drift of a parachute-retarded weapon. Aircraft typically laid Starvation minefields at night, under radar navigation and at altitudes ranging from 200 to 30,000 feet. Bombers would drop mines in a straight line in a planned location, sometimes with individual mines landing ashore.16 About 50 percent of the emplaced mines were dropped within a half mile of their intended location.17

The same techniques are used today, often requiring multiple passes with inaccurate, parachute-retarded mines. A B-52 mine-laying pass occurs at 500 feet and 320 knots—too slow to be safe in fighters or the B-1B. The F-18 and P-3 employ similar profiles, leaving the laying aircraft low, slow, and predictable—a contributor to the loss of one aircraft and crew in Desert Storm’s only mine-laying attempt.

The Twenty-First-Century Aerial Mine

Aerial mining techniques have not advanced since the Second World War, but the demonstration of Quickstrike-ER changed the picture entirely, mixing a modern mine with both precision and standoff. The Mk-82/-83/-84-series bomb bodies can be fitted with JDAM kits, which convert the weapon into a GBU-38/-32/-31, respectively.

The short range of the JDAM provides little standoff, but the addition of a wing kit corrects that deficiency. The GBU-62B(V-1)/B Quickstrike-ER is Pacific Air Forces’ nomenclature for an Mk-62 Quickstrike configured with a BSU-104 JDAM-ER wing and the GBU-38’s guidance kit. The range of the system is in excess of 40 nm when launched from 35,000 feet.

These kits, applied to the Mk-62 Quickstrike, allow both precision delivery and “one-pass” standoff mine laying from either medium or high altitude.18 A bomber aircraft with a full load of guided Quickstrike-ERs can lay an effective minefield with a single release sequence. Mines with guidance kits can be laid in an unpredictable pattern, making mine clearance that much more difficult; furthermore, they can be tailored to the characteristics of specific waterways.

The Twenty-First-Century Aerial Minelayer

The implications for the Quickstrike-ER (fig. 2) go beyond precision, allowing aircraft to emplace mines from range. Today, only F-18, P-3, B-1, and B-52 crews train for mining. JDAM training, on the other hand, is ubiquitous. There is no practical difference between JDAM employment against a fixed ground target or a fixed location under shallow water; no additional training for basic mine laying is required.

The addition of low observable aircraft to the stable of potential standoff minelayers introduces two new capabilities to the mix. The first is the possibility of laying minefields within the outer limits of a target country’s air defenses. The second is the potential to air-deliver a minefield covertly.

Mine Warfare

Typically, aerial delivery of mines is offensive mine warfare because mines are emplaced in a country’s home waters. This technique is effective for maritime interdiction (Starvation, 1945), port closure (Hanoi, 1972), or even antisurface warfare (Palau, 1944). Offensive mining of inland waterways interdicts local traffic, a technique used extensively in Germany, Burma, China, and Vietnam. Unlike the RAF, the US Air Force has never used aerial mining for defensive purposes.

The collateral effect of mining extends beyond simple target destruction. Fear of mines is likely to interdict more shipping than actual mine detonation, and the requirement under the Hague Convention of 1907 to declare minefield danger zones actually increases the effect. All Eastern Bloc vessels in Hanoi remained for the duration—even though the United States gave 72 hours’ notice of minefield activation. During mining of the Hanoi harbor, no ship challenged the minefield or made an attempt to clear it. For commercial vessels, the increase in insurance rates in a declared danger zone can be prohibitive, causing ships to avoid mined or potentially mined areas entirely. Ambiguity is key; a mined zone must be declared, but not all declared zones must be mined.

Introduction of the TDD has improved the specificity of mines. The new Mk-71 Mod 1 TDD is software programmable and has different algorithms for various classes, including submarines, minisubs, air-cushion vehicles (hovercraft), and fast patrol boats, allowing the mine to classify and select the desired target. The Mk-71 can distinguish between actual targets and decoys or countermeasure devices. This capability might allow for tailored mining, intended to interdict one kind of vessel but not another.

Never before has aerial mining been conducted with either precision or standoff. The emergence of this kind of capability not only will enable more effective and easier offensive mining but also will allow for short-notice defensive mining and a new category—reactive mining.

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Notes

1. “Damn the torpedoes; full speed ahead!” This oft-misquoted comment by Adm David Farragut at Mobile Bay refers to mines, which at the time were referred to as torpedoes. Samuel Colt demonstrated the moored, command-detonated mine in 1844.

2. Maj John S. Chilstrom, Mines Away! The Significance of US Army Air Forces Minelaying in World War II (Maxwell AFB, AL: Air University Press, 1993), 13.

3. H. L. Thompson, New Zealanders with the Royal Air Force, vol. 2, European Theatre, January

1943–May 1945 (Wellington, New Zealand: War History Branch, Department of Internal Affairs, 1956), chap. 5, external pagehttp://nzetc.victoria.ac.nz/tm/scholarly/tei-WH2-2RAF-c5.htmlcall_made.

4. Chilstrom, Mines Away!, 25.

5. Ibid., 21.

6. Ibid., 22.

7. Ibid., 29.

8. Wesley Frank Craven and James Lee Cate, eds., The Army Air Forces in World War II, vol. 5, The Pacific: Matterhorn to Nagasaki, June 1944 to August 1945 (1953; new imprint, Washington, DC: Office of Air Force History, 1983), http://www.ibiblio.org/hyperwar/AAF/V/AAF-V-21.html; and CAPT Gerald A. Mason, USN, “Operation Starvation,” AU/AWC/2002-02 (Maxwell AFB, AL: Air War College, 2002), 7, external pagehttp://www.au.af.mil/au/awc/awcgate/awc/2002_mason.pdfcall_made.

9. Craven and Cate, Pacific: Matterhorn to Nagasaki, 674.

10. Chilstrom, Mines Away!, 43.

11. Edward J. Marolda, “U.S. Mining and Mine Clearance in North Vietnam,” in Encyclopedia of the Vietnam War: A Political, Social, and Military History, ed. Spencer C. Tucker (Santa Barbara, CA: ABC-CLIO, 1998), external pagehttp://www.history.navy.mil/wars/vietnam/minenorviet.htmcall_made.

12. Sabrina R. Edlow, U.S. Employment of Naval Mines: A Chronology (Alexandria, VA:

Center for Naval Analyses, 1997), 7.

13. Ibid., 11.

14. Mason, “Operation Starvation,” 12.

15. Depths of 10–40 feet are considered very shallow, and less than 10 feet is considered

the surf zone.

16. “Figure from XXI Bomber Command Tactical Mission Report, Field Order No. 16, Mission No. 47, 313th Bombardment Wing, May 19, 1945,” in Mason, “Operation Starvation,” 18.

17. Mason, “Operation Starvation,” 14.

18. The stock GBU-38 tail kit will not fit on a Quickstrike mine with an Mk-71 TDD. An Mk-57 TDD might fit with a minor modification, but it is not a field modification.