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.
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.
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.
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Defense Systems of
Other Countries
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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.
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.
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.
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.
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.
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Coordination and
Command
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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.
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DEFENSIVE WARNING
SYSTEMS
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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.
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.
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.
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.
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Antiballistic
Missile Systems
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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.
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EXISTING NUCLEAR
THREATS
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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.