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SABMIS (Sea Based Anti-Ballistic Missile Intercept System)

In 1967, Secretary McNamara settled the debate over deploying the Nike-X ABM system. The failure of the Johnson Administration to reach an arms control agreement with the Soviets in June 1967, and China’s detonation of its first hydrogen bomb that month, influenced Secretary McNamara to announce the deployment of a thin anti-Chinese ABM system based on the Nike-X system in September 1967. In November, he subsequently announced that the new ABM system would be renamed Sentinel.

In 1967, the Navy and Air Force also developed ABM system concepts. The Navy examined a midcourse ABM system concept called the Sea-Based Anti-Ballistic Missile Intercept System (SABMIS), which envisioned employing radars and interceptors mounted on surface vessels and interceptors on submarines. These vessels would have been deployed in the Northwestern Pacific and the North Atlantic to protect the continental United States from Soviet or Chinese attack, as well as helping defend America’s allies from off-shore positions.

In July 1967 USN selected six companies to compete for six-month study contract to design ship-based antimissile missile system which could support Nike-X. Companies were Hughes Aircraft Co., Martin Marietta Corp., Boeing Co., Aerojet-General Corp., McDonnell Douglas Co., and Raytheon Co. Code-named Seaborne Anti-Ballistic Missile Intercept System, it would be deployed on submarines and warships stationed in international waters off Communist China and USSR to intercept long-range missiles launched from those countries.

A USA Nike-X official commented : "The Navy system is both feasible and attractive. It could intercept enemy icbm's before they can deploy most of their penetration aids; it would reduce the number of missiles Nike-X would have to contend with ; and it would tremendously increase the enemy's technology problems by forcing him to become very sophisticated indeed if he wants to stand any chance of getting his ICBm's past both the mid-course and terminal phase defenses."

Addressing the House in September 1967 on means for a terminal-phase missile interception system, Rep. William R, Anderson (D-Tenn.) called for a sea-based antiballistic missile intercept system. Pointing to the popular estimate that Red China would have a ballistic missile delivery capability in the early 1970s, the Congressman stated: ". . . deployment of a SABMIS unit would place in the seas close to an adversary's homeland and across his 'launch trajectory window,' a mobile, partly submerged screen of antimissile forces."

The Navy conducted extensive investigations in fiscal year 1968 of a very promising baseline design, the Sea-Based Ballistic Missile Intercept System (SABMIS). Sabmis involved deploying surface ships equipped with Spartan or Polaris missiles to intercept incoming missiles before warhead dispersal takes place. From a sea based anti-ballistic missile system accrue the advantages of mobility, early midcourse intercept, and defense-in-depth, as well as a capability against the Fractional Orbital Bombardment System (FOBS).

The SABMIS concept was offered by the Navy as a supplement and possibly alternate to the "thin" Safeguard/Nike-X Anti-Ballistic Missile (ABM) system proposed by the Nixon Administration. Although certain factions within the Navy and in the Congress have advocated a comparative analysis of the proposed SABMIS and Safeguard concepts, the official policy of the Departments of Defence and Navy has been to consider SABMIS only as a study for a backup or "in depth" complement to the Safeguard system. Reportedly, approximately $3,000,000 has been spent on SABMIS compared to approximately $4 billion on Safeguard Nike-X studies, research, and development. In view of the existing political situation with President Nixon's Administration firmly committed to a policy of deploying the Safeguard system, it appears unlikely that SABMIS could be developed so long as there is any interest in the Safeguard system. The proposed SABMIS ship is described on a subsequent page of the listings for Strategic Warfare Ships.

SABMIS was to be composed of elements similar to those of the Nike-X system mounted on large ships. With the ability to move these ships forward to positions around the periphery of the Soviet Union, it would be possible to detect the launch of enemy missiles and intercept them during the boost or mid-course phase of their flight trajectory. The radar to detect an enemy ICBM launching, the fire control computers, missile guidance, and the ABM missile launchers would all be mounted in a single ship under the SABMIS concept. It is anticipated that an extremely small number of ships could provide the capability of intercepting the approximately 40 intercontinental missiles which Communist China would be able to launch against the United States in the mid-1970s.

Also, the SABMIS concept could provide a low-cost "thin" defence against an "accidental" Soviet ICBM launching of a small number of missiles against the United States. (Most authorities agree there is today no possiblity of providing defence against an all-out Soviet ICBM strike against the United States). However, even against a threat of this size a force of several SABMIS ships may be desired, to provide for survivability in the event of war and for normal overhaul and training. Still, a multi-ship SABMIS force, with nuclear powered-escort ships, is expected to cost considerably less than the $8 to 40 billion Safeguard, Nike-X "thin" ABM defence now being proposed for the United States.

The problems of detecting and destroying an ICBM' during the launch-boost stage is far less complicated than seeking to locate and destroy several re-entry packages (warheads and decoys). The Safeguard/Nike-X ABM is a "sector system" with each of the planned 12 missile sites defending a sector of the United States. Thus, each site must have the capability of intercepting all intercontinental missiles which China is expected to have available in the mid-1970s. However, a single SABMIS ship could be positioned to intercept virtually all missiles being fired at the United States because of the limited China-to-United States ICBM trajectory spectrum.

The research and development and operating costs of eight ships over ten years was estimated at $5.9 billion. In a "Draft Memorandum From Secretary of Defense Clifford to President Johnson" dated July 28, 1968, Secretary of Defense Clark Clifford recommended that the President reject the Joint Chiefs of Staff recommendation for Contract Definition on a ballastic missile ship in FY 1970. While receiving some attention, the studies were eventually discontinued due to the vulnerability of the ships in the forward basing areas.

The Air Force had a similar concept called the Airborne Ballistic Missile Intercept System (ABMIS), which would have been used against low-trajectory attacks from submarine-launched ballistic missiles. ABMIS envisioned radars and interceptors mounted on specially equipped aircraft, such as the C-5A, on around-the-clock patrols adjacent to major cities overseas.

In May 1972, arms control talks with the Soviets produced the Anti-Ballistic Missile (ABM) Treaty, which restricted the deployment of any strategic space-based, sea-based, or mobile ABM systems, such as SABMIS and ABMIS. The treaty allowed each side only two fixed missile defense sites: one to defend national command authorities, and one to defend a missile field, with no more than 100 total interceptors for both sites. A 1974 protocol subsequently reduced the number of sites to one.

Displacement20,000-30,000 tons, full load
Length approx 700 feet (215 meters)
Missiles approx 40-60 ABM interceptors
Several Point Defense Missile System (PDMS) launchers
Propulsion 2 pressurised-water cooled Nuclear reactors
Main engines Geared turbines, 2 shafts

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Page last modified: 07-07-2014 19:41:05 ZULU