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Total involvement of all participants characterizes modern warfare; rear areas are no longer secure. Army watercraft units must perform their operational mission regardless of the levels of threat in the theater. Commanders and leaders must recognize the threat and know each unit's vulnerability to it. The threat force concept of operation is based on the expectation that future warfare will be highly mobile. All means of inflicting casualties on the enemy will be used.

Because watercraft units must be prepared to operate anywhere, it is impossible to describe specific threat forces, equipment, or doctrine. This chapter focuses on types of threats common to all watercraft units and ways to defeat them. If the threat is based on the Soviet model, FMs 100-2-1, 100-2-2, and 100-2-3 are used. Remember, watercraft units may face weapons systems from all over the world, including the United States (US).


Threats can generally be classified as coming from air, water, or land forces; the electronic warfare (EW) environment; or the nuclear, biological, and chemical (NBC) environment. Watercraft units are particularly at risk because ports and terminals are prime targets for threat forces. Appendix A covers NBC threat.

Air Threat

The air threat consists of--

  • Fixed- or rotary-wing aircraft. Both fixed- and rotary-wing aircraft can operate at night and use a variety of cannon, guns, bombs, and missiles to attack targets. Precision-guided munitions let aircraft selectively attack individual boats.

  • Remotely piloted vehicles (RPVs). RPVs are used for reconnaissance and targeting platforms. They use a variety of photo, infrared (IR), thermal, and electronic devices to locate potential targets.

  • Long- or medium-range missiles. Missiles can deliver conventional or special ordnance over a very large area. Missile systems today can impact within 200 meters of the intended target.

Water Threat

The water threat consists primarily of--

  • Other surface craft. Surface craft include every craft from rubber boats to battleships. Of primary concern are fast patrol boats which can operate close to the shore and on rivers.

  • Subsurface craft. Army watercraft are not likely targets for submarines, but it is possible, especially for the logistics support vessels (LSVs).

  • Mines. Many types of mines including freed and free-floating mines are available to threat forces. A variety of means including physical contact, magnetic fields, or sound detonate these mines. They often include some type of anti-handling device.

  • Swimmers. Special operations forces threaten Army watercraft by swimming or otherwise infiltrating an area and performing reconnaissance or sabotage.

Land Forces Threat

Land forces present a spectrum of threats ranging from individual saboteurs to large conventional forces. The greatest threat from a large land force might occur during the early stages of an amphibious operation before the beachhead is secure. A more realistic scenario is that small teams of saboteurs or terrorists would try to disrupt operations. The threat from artillery and short-range missile fire directed against watercraft operations is significant.

Electronic Warfare Threat

Electronic warfare threatens watercraft operations because of our reliance on electronic communications equipment. Threat forces can intercept or jam communications and can target transmitters using direction-finding equipment linked to indirect fire delivery systems.


The first priority in countering the threat is to identify it. Since watercraft units rarely operate on their own, usually a higher command will assist them. The S2, G2, or J2 should provide a detailed analysis of the types of threat forces available, their capabilities, and probable courses of action. Specific countermeasures can then be effected. Sections of watercraft units that are on the beach or shore should counter all threats according to doctrine for land forces.

Defense Against the Air Threat

Defending against the air threat involves passive and active measures.

Passive Measures. Passive measures include using maximum cover and concealment, dispersing, and reducing heat and electronic signatures. Whenever possible, watercraft units should use nets or tarps to cover the boat or its cargo. The threat may prioritize targets by cargo importance. Units should seek cover in coves, inlets, or small harbors that are difficult to attack from the air. All vessels should be hardened using sandbags or metal plate to protect crew quarters and/or crew stations. Any hardening adds to the weight of the vessel and must be considered. Watercraft units should disperse whenever possible to reduce the risk of multiple hits or sympathetic explosions from a single aircraft pass. Light discipline should be strictly enforced.

Active Measures. Active measures include using all available weapons against attacking aircraft. The watercraft unit commander must know the air defense plan for the area of operations. Air attack warnings, weapons status, and self-defense procedures must be thoroughly understood and integrated. Because a watercraft unit cannot defeat an inbound missile by itself, the best defense lies in the measures of dispersing and hardening. Boat crews may deceive the enemy by burning diesel fuel and scraps in a fireproof container. The smoke may fool threat forces into believing the vessel has been hit. If the situation allows and forces are available, air defense teams can ride on vessels to provide short-range defense.

Defense Against the Water Threat

Defending against a water threat is much more difficult than against air threat. Although the US Navy and the US Coast Guard (USCG) are responsible for offshore security, watercraft units must constantly guard against attack from the water. The same passive measures described above apply to water threat.

Active Measures. Active measures include --

  • Using evasive action to outrun or out-maneuver the attacker. US Army watercraft are not particularly fast or agile, so it will be difficult to adopt this in open water.

  • Using all organic weapons to defeat the threat. Again, the light armament aboard watercraft renders this option fairly ineffective. Escorts, both vessel and aircraft, can provide security and firepower. All options to increase firepower on board the vessel such as adding MK 19 grenade launchers, should be explored. Options are limited only by what can be carried on board, weapons available, and whether the situation will allow forces to support the watercraft units.

  • Trying to run the attacking vessel aground by running for shallow water. Use the deception method described above.

  • Constantly watching for mines. When traveling independently, vessels must reduce speed, and crews must watch for mines. The crew must put on life jackets and prepare survival gear in case they must abandon ship. Units must report the location of mines immediately and request operations cease until mines are cleared.

  • Using underwater barriers, counter-swimmers, concussion grenades, and searchlights to defeat underwater swimmers. These measures must be part of an integrated plan so that they do not violate the overall defensive scheme.

Defense Against the Land Threat

Land forces significantly threaten watercraft units. During amphibious offensive or retrograde operations, land forces may directly fire on watercraft units. The mission dictates whether the watercraft can leave the area or must continue to operate. If they must continue, all weapons and supporting unit weapons must be used. Smoke could be used to screen operations.

Land forces could be far enough away that water units are only within indirect fire range. Again, the mission dictates whether the unit must remain in the area. The same passive measures discussed above apply. In addition, sections that are ashore need to protect themselves with bunkers or other types of shelters. A more probable threat comes from special operations forces, saboteurs, and terrorists. Counterterrorist measures outlined in FM 100-37 provide an effective defense against all Level 1 threats.

Defense Against Electronic Warfare Threat

FM 24-1 best describes how to counter electronic warfare. These measures fully apply to watercraft units.

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