Air Defense Systems

Air Defense Systems, combination of electronic warning networks and military strategies designed to protect a country from a strategic missile or bomber attack. Air defense systems use radar and satellite detection systems to monitor a nation’s airspace, providing data that would allow defense forces to detect and coordinate against such an attack. Several industrialized nations, including the United States, also maintain an arsenal of offensive nuclear weapons as a deterrent to a nuclear attack.

II

STRATEGIC DEFENSE

Modern air defense systems originated during World War II (1939-1945) in response to the advent of long-range bomber aircraft. Radar stations in Great Britain were installed to detect approaching German bombers and give British fighter aircraft time to intercept the enemy. Before World War II, most nations focused national defense against assaults from land or sea.

After World War II, the United States enjoyed a brief period of military superiority as the sole possessor of nuclear weapons, but the detonation of an atomic bomb by the Union of Soviet Socialist Republics (USSR) in 1949 brought a new military threat. The United States began to focus its defenses on early detection of long-range bombers, to give U.S. fighter aircraft enough time to respond to a large-scale attack.

The ballistic missile threat was the most important development in air defense systems. When the first German V-2 ballistic missiles arced over England on September 6, 1944, a new day in warfare dawned. The V-2 traveled at supersonic speeds and was impossible to intercept. After World War II an immediate missile race began between the United States and the USSR. The goal was to build upon German technology and create a long-range intercontinental ballistic missile, or ICBM, that could deliver a nuclear warhead.

A

Deterrence

By 1958 both the United States and the USSR had successfully tested ICBMs and immediately began to improve them. As a result, both nations became extremely vulnerable to attack. The amount of warning that existing national radar systems could provide for an incoming bomber attack had been measured in hours, but an ICBM could loft from a launching base in the USSR and impact in the United States within 30 minutes. There were no technical means to stop a missile once launched, so national leaders turned to the idea of deterrence.

Deterrence uses the threat of an offensive attack as a defense—or deterrent—against such an attack. The USSR, with its initial lead in rocket and missile technology, had adopted a so-called first strike strategy. The Soviet leaders recognized that an exchange of nuclear missiles would be so devastating to both countries that the USSR had to launch its missiles first, and in such numbers that a crippled United States would not be able to mount a significant retaliatory strike. The United States publicly said it would never undertake a first strike, deciding instead to develop a second-strike capability of such magnitude that no Soviet first strike would avoid retaliation. This strategy became known as mutually assured destruction, which had the appropriate acronym MAD. The arms buildup between the United States and the USSR, and the tensions surrounding the buildup, became known as the Cold War because no direct combat took place. Although the world came close to nuclear war on several occasions, such as during the Cuban Missile Crisis, the USSR never dared to launch a first strike, so the United States never had to retaliate.

B

Defense Systems of Other Countries

Although the Cold War ended in the early 1990s, major military powers continue to employ some version of offensive deterrent and defensive warning capability. Shortly after World War II, political and military alliances were created to offer mutual defense. The United States, Britain, France, and several other countries formed the North Atlantic Treaty Organization (NATO), while the USSR and its satellite countries responded with the Warsaw Pact. Almost all countries monitor their own airspace, but for strategic defense—that is, for protection against nuclear attack—the members of these alliances generally looked to either the United States or the USSR for protection.

III

OFFENSIVE DETERRENTS

Several countries such as the United States, Russia, Britain, France, and China maintain a force of offensive nuclear weapons to deter against a nuclear attack. The offensive capability of the United States rests on what is known as the Nuclear Triad, comprised of strategic bombers, land-based ICBMs, and submarine-launched ballistic missiles. The triad was devised so if any one of the three “legs” is destroyed by an attack, the other two can still function. The nuclear powers of the world maintain some or all of these forces.

A

Bombers

From 1945 through about 1960, the United States had depended upon the bomber aircraft of the Strategic Air Command (SAC) to deter an attack from the USSR. In the early years of SAC, these aircraft included the Boeing B-50 and the Consolidated B-36. Later jets such as the Boeing B-47 Stratojet and Boeing B-52 Stratofortress jet bombers were faster and could carry more payload. The United States currently maintains B-52, Rockwell B-1B, and Northrop Grumman B-2 bombers capable of being armed with nuclear weapons as part of its strategic force.

B

ICBMs

The USSR began an intensive ICBM development program after World War II, and the United States responded in kind. While the Soviet bomber fleet never approached that of the United States in size or capability, the Soviet ICBM fleet was truly formidable. The USSR developed greater numbers of ICBMs than the United States, and these had larger warheads, greater range, and superior accuracy to U.S. weapons. The USSR also was successful in hardening (or making resistant to a nuclear attack) its silo launch facilities to a far greater degree than the United States was able to do.

C

SLBMs

A similar process followed for the submarine-launched ballistic missile (SLBM), when in the late 1950s the USSR built several submarines able to carry the SS-N-4 Sark missile. In 1960 the United States sent the USS George Washington on patrol, carrying Polaris SLBMs. As technology improved, the SLBM assumed greater importance. A ballistic missile submarine is difficult to detect, can remain on duty for weeks at a time without surfacing, and can fire its missiles from beneath the water’s surface.

D

Coordination and Command

The U.S. Strategic Command was created to monitor defense information from various sources and coordinate a military response to a nuclear attack. The Strategic Air Command (SAC) was for many years the primary deterrent force. It has been replaced in part by the Air Combat Command. For many years as much as 50 percent of the SAC bomber fleet was on airborne alert, armed with nuclear weapons, and able to attack immediately upon notice.

In the event of an attack, the role of the U.S. Strategic Command was to collect data and present recommendations to the U.S. president and senior advisers (referred to as the National Command Authority). Only the president can make the decision to use nuclear weapons, even in response to an attack. The plan a president would use to respond to an attack is called the Single Integrated Operational Plan, or SIOP. The SIOP consists of several planned responses to various nuclear scenarios. If the U.S. president were to decide to use nuclear weapons, several procedures and code phrases would be used to verify the president’s authority. When the procedures are completed, they would authorize the military to use nuclear weapons. Numerous precautions exist in this process to prevent accidental or unauthorized use of nuclear weapons.

Under SIOP, the president and the rest of the National Command Authority would possibly give orders from a modified Boeing 747 called a National Airborne Operations Center (NAOC). By being airborne, command authority is less vulnerable to a ground attack. These airplanes are outfitted with advanced communications equipment so the president can stay in contact with U.S. Strategic Command at all times. The U.S. Strategic Command also has a number of airborne command centers that can coordinate military forces in the event that ground centers have been destroyed or damaged.

In 2002 the U.S. Strategic Command was merged with the U.S. Space Command. The role of the Space Command had been to monitor a global network of satellites and ground sensors that warn of missile launchings. The purpose of the merger was to create a single command responsible for both early warning against an attack and for responding to such an attack or for initiating an attack. The merger was seen as a step in implementing a new policy, outlined by President George W. Bush, of preemptive, or first-strike, attacks against nations that develop weapons of mass destruction, including biological and chemical weapons.

IV

DEFENSIVE WARNING SYSTEMS

The consequences of a nuclear exchange would be devastating, with casualties estimated to be in the hundreds of millions on both sides and massive damage to the environment. Both the USSR and the United States were aware of the catastrophic scale of a nuclear exchange, and both built elaborate defensive systems to detect an incoming nuclear attack.

A

Radar Networks

From 1949 (when the USSR developed nuclear weapons) to 1959 (when ICBMs became operational), the main strategic threat was bombers. To provide advance warning, several radar posts were built across Canada by joint cooperation between Canada and the United States. The first series of linked radar stations was called the Pinetree Line, established in 1954. Two more lines, the Mid-Canada Line and the Distant Early Warning Line (or DEW Line), were created for more complete radar coverage. The DEW Line, comprising 60 radar sites along the 70th parallel, became operational in 1957.

To warn against ICBMs, the Ballistic Missile Early Warning System (BMEWS) was introduced in 1962. It consisted of sophisticated radar sites in Greenland, Alaska, and England. These sites could detect, track, and predict impact points of both intercontinental ballistic missiles and smaller intermediate range ballistic missiles (IRBMs) launched from within the USSR. A typical site has four giant scanner search radars, each 50.3 m (165 ft) high and 122 m (400 ft) long, and one tracking radar, a 25.6 m (84 ft) antenna in a 42.6 m (140 ft) diameter housing. The purpose of the BMEWS is to provide sufficient warning time for U.S. bombers to get airborne and ICBM forces to prepare for a counterstrike.

The BMEWS was backed up by the Perimeter Acquisition Radar Characterization (PARCS) system. Operating in the U.S. interior, PARCS can detect air traffic over Canada. Four other radar sites monitor the Atlantic and Pacific oceans for possible submarine attacks. These various stations were connected to the North American Aerospace Defense Command (NORAD), to U.S. Strategic Command headquarters, the Pentagon, and to the Canadian Royal Air Force fighter command.

B

NORAD

NORAD was activated in 1957 to provide an integrated command for the air defense of the United States and Canada, and to process the information gathered from various radar sites. The reality of ICBMs required the establishment of a detection and tracking system, and the housing of NORAD in a bombproof site located within the interior of Cheyenne Mountain near Colorado Springs, Colorado. With its increased responsibility, NORAD equipment was expanded to include the Airborne Warning and Control Aircraft (AWACS), Over the Horizon (OTH) radar that warns against low-altitude cruise missiles, and a network of satellites. The DEW Line was replaced with a superior system called the North Warning System, and the Joint Surveillance System (JSS), operated by the U.S. Air Force and the Federal Aviation Administration, provides additional air traffic coverage. NORAD was later renamed the U.S. Space Command. As a result of the 2002 merger between the Space Command and the Strategic Command, the joint Space Command/Strategic Command monitors all of these early warning systems.

C

Soviet Air Defense

The USSR built an even more extensive integrated air defense system, covering the country with radar systems, surface-to-air missile sites, and large numbers of interceptors (fast military aircraft designed to destroy attacking airplanes). The USSR built a huge infrastructure of civil and military defense systems, including deep underground blast shelters for the country’s leaders and key industries. Following the breakup of the USSR in 1991, only a remnant of this civil defense network remained in Russia. The United States abandoned its rather primitive civil defense efforts of the 1950s and has not replaced it with any other system.

D

Antiballistic Missile Systems

Active defense systems have been proposed that would use interceptor missiles to track and shoot down incoming ICBMs detected and tracked by radar. These are known as antiballistic missile (ABM) or ballistic-missile defense (BMD) systems. The most important U.S. antiballistic missile systems were the 1967 “Sentinel,” the 1969 “Safeguard,” and the Strategic Defense Initiative (SDI), which was proposed by U.S. president Ronald Reagan in 1983. SDI would have used a combination of satellite-based sensors and weapons to destroy ballistic missiles after their launch. The research that began on SDI continued in various ways, but no actual program was started because costs were deemed too high.

The 1972 Anti-Ballistic Missile (ABM) Treaty signed by the United States and the USSR limited the implementation of antiballistic missile systems. Russia developed one system around Moscow, and this system still exists although it is very old. The United States had a system in North Dakota but closed it down due to cost and reliability issues. However, in 2001 the administration of United States president George W. Bush announced that it was unilaterally withdrawing from the ABM Treaty. Bush called for the creation of a rudimentary missile defense system by 2004. Some critics of the decision called it destabilizing because other nations could interpret it as a move by the United States toward a first-strike strategy. Other critics of the decision focused on the problematic costs and reliability of ABM systems. See also Arms Control.

Another defensive system against missile attacks is the Patriot missile, which is designed to destroy shorter-range ballistic missiles, such as the Scud missiles used by Iraq during the 1991 Persian Gulf War. Patriot missiles were also used by U.S. forces during the 2003 invasion of Iraq. The United States also indirectly defends against some missiles through the antisubmarine warfare combination of undersea surveillance and the use of attack submarines and surface ships to track Russian ballistic missile submarines. While none of these weapons can intercept an enemy missile once launched, they can track and destroy the submarine itself.

V

EXISTING NUCLEAR THREATS

With the end of the Cold War between the former Soviet Union and the United States, the threat of an all-out nuclear attack has greatly diminished. It is highly unlikely that Russia would ever launch a massive first strike against the United States, and both countries have significantly reduced their nuclear forces. Under the terms of an arms reduction treaty signed in 2002 between the United States and Russia, both nations agreed to reduce their strategic nuclear arsenals to about 2,200 nuclear warheads by the year 2012. Still, the threat of nuclear war remains because of the spread of nuclear weapons. In 1998 India and Pakistan conducted nuclear bomb tests. In 2003 North Korea told U.S. officials that it possessed nuclear weapons. Only five nations have openly revealed the number of nuclear weapons they possess. They are China, France, Russia, the United Kingdom, and the United States. As of 2002, the number of nuclear weapons each nation possessed was China (434), France (482), Russia (about 6,000), the United Kingdom (200), and the United States (about 6,000). Israel is known to have the capability to deploy some 100 nuclear weapons. See also Strategic Arms Limitation Talks, Arms Control.