Editing Naval mine (section)

=== Active countermeasures ===
Active countermeasures are ways to clear a path through a minefield or remove it completely. This is one of the most important tasks of any mine warfare flotilla.

==== Mine sweeping ====
[[File:MH-53E Sea Dragon towing sled.jpg|thumb|An [[CH-53E Super Stallion|MH-53E]] from [[HM-15]] tows a [[minesweeping]] sled while conducting simulated mine clearing operations]]
[[File:USS Tide sinking.jpg|thumb|[[Minesweeper]] {{USS|Tide|AM-125|6}} after striking a mine off [[Utah Beach]], 7 June 1944. Note her broken back, with white smoke billowing amidships.]]
{{main|Minesweeping}}

A sweep is either a contact sweep, a wire dragged through the water by one or two ships to cut the mooring wire of floating mines, or a distance sweep that mimics a ship to detonate the mines. The sweeps are dragged by [[minesweeper (ship)|minesweeper]]s, either purpose-built military ships or converted [[Commercial trawler|trawlers]]. Each run covers between {{convert|100|and|200|m|ft|spell=in}}, and the ships must move slowly in a straight line, making them vulnerable to enemy fire. This was exploited by the Turkish army in the [[Battle of Gallipoli]] in 1915, when mobile [[howitzer]] batteries prevented the British and French from clearing a way through minefields.

If a contact sweep hits a mine, the wire of the sweep rubs against the mooring wire until it is cut. Sometimes "cutters", explosive devices to cut the mine's wire, are used to lessen the strain on the sweeping wire. Mines cut free are recorded and collected for research or shot with a deck gun.<ref>{{cite web |url=http://www.ussimplicitmso-455.com/Minesweeping.html |archive-url=https://web.archive.org/web/20090402163450/http://www.ussimplicitmso-455.com/Minesweeping.html |archive-date=2009-04-02 |title=Mine Sweeping Operations |work=Minesweeping |publisher=Charles Lees |access-date=2011-12-31 |url-status=dead }}</ref>

Minesweepers protect themselves with an [[Oropesa (minesweeping)|oropesa]] or [[Paravane (weapon)|paravane]] instead of a second minesweeper. These are torpedo-shaped towed bodies, similar in shape to a [[Harvey torpedo]], that are streamed from the sweeping vessel thus keeping the sweep at a determined depth and position. Some large warships were routinely equipped with paravane sweeps near the bows in case they inadvertently sailed into minefields—the mine would be deflected towards the paravane by the wire instead of towards the ship by its wake. More recently, heavy-lift helicopters have dragged minesweeping sleds, as in the 1991 Persian Gulf War.<ref>{{cite web |url=http://www.merriam-webster.com/dictionary/paravane |title=Paravane – Definition and More from the Free Merriam-Webster Dictionary |publisher=Merriam-webster.com |access-date=2011-12-31 |archive-date=28 January 2012 |archive-url=https://web.archive.org/web/20120128171755/http://www.merriam-webster.com/dictionary/paravane |url-status=live }}</ref>

The distance sweep mimics the sound and magnetism of a ship and is pulled behind the sweeper. It has floating coils and large underwater ''drums''. It is the only sweep effective against bottom mines.

During WWII, [[RAF Coastal Command]] used [[Vickers Wellington]] bombers Wellington DW.Mk I fitted with degaussing coils to trigger magnetic mines.<ref>{{cite web |url=http://www.wwiivehicles.com/unitedkingdom/aircraft/bomber/vickers-wellington.asp |title=Britain's Vickers Wellington bomber, 'Wimpey' |work=World War II Vehicles, Tanks, and Airplanes |publisher=Wwiivehicles.com |access-date=2011-12-31 |archive-url=https://web.archive.org/web/20111118105920/http://www.wwiivehicles.com/unitedkingdom/aircraft/bomber/vickers-wellington.asp |archive-date=2011-11-18 |url-status=dead }}</ref> In a parallel development the Luftwaffe adapted some Junkers 52/3m aircraft to also carry a coil operated by electricity supplied from an onboard generator. The Luftwaffe called this adaption ''Minensuch(e)'' (lit. mine-search).{{Sfn|Smith|1966|p=16}} In both cases pilots were required to fly at low altitude (up to about 200 feet above the sea) and at fairly low speeds to be effective.

Modern influence mines are designed to discriminate against false inputs and are, therefore, much harder to sweep. They often contain inherent anti-sweeping mechanisms. For example, they may be programmed to respond to the unique noise of a particular ship-type, its associated magnetic signature and the typical pressure displacement of such a vessel. As a result, a mine-sweeper must accurately mimic the required target signature to trigger detonation. The task is complicated by the fact that an influence mine may have one or more of a hundred different potential target signatures programmed into it.<ref name="ReferenceB">{{cite web |url=https://fas.org/man/dod-101/navy/docs/swos/cmd/miw/Sp6-4-1/sld034.htm |title=Mine Counter-Counter Measures (MCCM) |last=Garrold |first=Tim |work=Mine Warfare Introduction: The Threat |publisher=Surface Warfare Officers School Command, U.S. Navy |date=December 1998 |access-date=2011-12-31 |archive-date=4 March 2016 |archive-url=https://web.archive.org/web/20160304064742/http://fas.org/man/dod-101/navy/docs/swos/cmd/miw/Sp6-4-1/sld034.htm |url-status=live }} Slide 34 of 81. Hosted by Federation of American Scientists.</ref>

Another anti-sweeping mechanism is a ship-counter in the mine fuze. When enabled, this allows detonation only after the mine [[fuze]] has been triggered a pre-set number of times. To further complicate matters, influence mines may be programmed to arm themselves (or disarm automatically—known as ''self-sterilization'') after a pre-set time. During the pre-set arming delay (which could last days or even weeks) the mine would remain dormant and ignore any target stimulus, whether genuine or false.<ref name="ReferenceB"/>

When influence mines are laid in an ocean minefield, they may have various combinations of fuze settings configured. For example, some mines (with the acoustic sensor enabled) may become active within three hours of being laid, others (with the acoustic and magnetic sensors enabled) may become active after two weeks but have the ship-counter mechanism set to ignore the first two trigger events, and still others in the same minefield (with the magnetic and pressure sensors enabled) may not become armed until three weeks have passed. Groups of mines within this mine-field may have different target signatures which may or may not overlap. The fuzes on influence mines allow many different permutations, which complicates the clearance process.<ref name="ReferenceB"/>

Mines with ship-counters, arming delays and highly specific target signatures in mine fuzes can falsely convince a belligerent that a particular area is clear of mines or has been swept effectively because a succession of vessels have already passed through safely.

==== Minehunting ====
[[File:Minenjagddrohne Pinguin.jpg|thumb|''Pinguin B3'' minehunting drone, such are operated from {{sclass|Frankenthal|minehunter|1}}s of the [[German Navy]]]]
{{main|Minehunting}}

As naval mines have become more sophisticated, and able to discriminate between targets, so they have become more difficult to deal with by conventional sweeping. This has given rise to the practice of minehunting. Minehunting is very different from sweeping, although some [[minehunter]]s, known as [[Mine countermeasures vessel|mine countermeasures vessels (MCMVs)]] can do both tasks.  Minehunters use specialized high-frequency sonars and high fidelity sidescaning sonar to locate mines, which are then inspected and destroyed either by divers or [[Remotely operated underwater vehicle|ROV]]s (remote controlled unmanned mini-submarines).<ref name="minewar" />{{rp|18}} It is slow, but also the most reliable way to remove mines, as it circumvents most anti-minesweeping countermeasures. Minehunting started during the Second World War, but it was only after the war that it became truly effective.

Sea mammals (mainly the [[bottlenose dolphin]]) have been trained to hunt and mark mines, most famously by the [[U.S. Navy Marine Mammal Program]]. Mine-clearance dolphins were deployed in the [[Persian Gulf]] during the [[Iraq War]] in 2003. The US Navy claims that these dolphins were effective in helping to clear more than 100 antiship mines and underwater [[booby trap]]s from [[Umm Qasr Port]].<ref>{{cite web |url=http://www.smithsonianmag.com/issues/2003/september/phenomena.htm |archive-url=https://archive.today/20070901162827/http://www.smithsonianmag.com/issues/2003/september/phenomena.htm |url-status=dead |archive-date=2007-09-01 |title=Uncle Sam's Dolphins |work=[[Smithsonian (magazine)|Smithsonian Magazine]] |date=September 2003 |access-date=2011-12-31 }}</ref>

French naval officer [[Jacques Yves Cousteau]]'s Undersea Research Group was once involved in minehunting operations: They removed or detonated a variety of German mines, but one particularly defusion-resistant batch—equipped with acutely sensitive pressure, magnetic, and acoustic sensors and wired together so that one explosion would trigger the rest—was simply left undisturbed for years until corrosion would (hopefully) disable the mines.<ref>Cousteau, Jacques Yves. ''The Silent World'', p. 58. New York: 1953, Harper & Row.</ref>
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==== Mine running ====
[[File:SeehundeTroika.jpg|thumb|[[Ensdorf class minesweeper|Seehund]] ROVs of the [[German Navy]] used for minesweeping]]

A more drastic method is simply to run a ship through the minefield, letting other ships safely follow the same path. An early example of this was [[David Farragut|Farragut]]<nowiki>'s</nowiki> [[Battle of Mobile Bay|actions at Mobile Bay]] during the [[American Civil War]]. However, as mine warfare became more developed this method became uneconomical.
This method was revived by the German [[Imperial German Navy]] during [[World War I]]. Left with a surfeit of idle ships due to the [[Blockade of Germany (1914–1919)|Allied blockade]], the Germans introduced a ship known as ''[[Sperrbrecher]]'' ("block breaker"). The type was also used during [[World War II]]. Typically an old cargo ship, loaded with cargo that made her less vulnerable to sinking (wood for example), the ''Sperrbrecher'' was run ahead of the ship to be protected, detonating any mines that might be in their path. The use of ''Sperrbrecher'' obviated the need to continuous and painstaking sweeping, but the cost was high. Over half the 100 or so ships used as ''Sperrbrecher'' in WWII were sunk during the war. Alternatively, a shallow draught vessel can be steamed through the minefield at high speed to generate a pressure wave sufficient to trigger mines, with the minesweeper moving fast enough to be sufficiently clear of the pressure wave so that triggered mines do not destroy the ship itself. These techniques are the only way to sweep pressure mines that is publicly known to be employed. The technique can be simply countered by use of a ship-counter, set to allow a certain number of passes before the mine is actually triggered. Modern doctrine calls for ground mines to be hunted rather than swept. A new system is being introduced for sweeping pressure mines, however counters are going to remain a problem.<ref>{{cite web |url=http://www.navysbir.com/n07_s/navst07-030.htm |title=Influence Sweeping of Pressure Mines |publisher=U.S. Navy Small Business Innovation Research |date=2007-03-21 |access-date=2011-12-31 |url-status=dead |archive-url=https://web.archive.org/web/20120308200055/https://www.navysbir.com/n07_s/navst07-030.htm |archive-date=2012-03-08 }}</ref><ref>{{cite web|url=http://www.janes.com/articles/Janes-Underwater-Warfare-Systems/Pressure-sweep-Sweden.html |title=Pressure sweep (Sweden) |work=Jane's Underwater Warfare Systems |publisher=Janes.com |date=2011-09-08 |access-date=2011-12-31}}</ref>

An updated form of this method is the use of small unmanned [[Remotely operated vehicle|ROV]]s (such as the [[Ensdorf class minesweeper|''Seehund'']] drone) that simulate the acoustic and magnetic signatures of larger ships and are built to survive exploding mines. Repeated sweeps would be required in case one or more of the mines had its "ship counter" facility enabled i.e. were programmed to ignore the first 2, 3, or even 6 target activations.

==== Counter-mining ====
Another expedient for clearing mines, especially in a hurry, is counter-mining. By this method an explosive is detonated in the area of a known or suspected minefield and the blast either trips off the fuzes or the actual explosive contained within the mine or mines. This latter is known as a [[sympathetic detonation]]. Counter-mining is normally used as a last resort or if other equipment is not available. One example was at the entrance to [[Grand Harbour]], Valletta, Malta in WW2 when the British dropped depth charges into the harbour entrance to detonate suspected mines prior to the arrival of an important convoy. It is especially useful against acoustic or pressure mines due to their activation by sound or increases in water pressure.