After the crisis, the USSR and United States opened a series of negotiations aimed at limiting the threat posed by nuclear war. The two nations, along with the United Nations' International Atomic Energy Agency, set about negotiating a way to limit the scope and dangers posed by the global atomic arms race.

		U.S. Military The limited test ban treaty prohibits nuclear tests in the atmosphere, in outer space and underwater.

The following is a list of the major agreements aimed at stabilizing, slowing and eventually reversing the nuclear arms race.

Partial Test Ban Treaty - 1963
Signed on Aug. 5, 1963 in Moscow, the treaty ended all nuclear weapons tests "or any other nuclear explosion" in the atmosphere, in outer space, or underwater in perpetuity. While not banning underground tests, the PTBT did prohibit underground nuclear explosions that cause radioactive debris to reach outside the territorial limits of the state where the explosions were conducted. France and China, both nuclear weapons countries, have never signed the treaty.

Non-Proliferation Treaty - 1968
Signed in the Soviet Union, the United States and the United Kingdom on July 1, 1968, the treaty sought to control the spread and use of nuclear technology for the manufacture of weapons. This pact pledged to restrict countries already in possession of nuclear weapons to refrain from giving control of those weapons to others and from transmitting information for their manufacture to states not possessing them. Countries without nuclear weapons that signed the pact agreed not to receive or manufacture them. The NPT also gave authority to the IAEA to police the nuclear activities of member countries to ensure nonproliferation. It has been approved by 187 countries, including all five major nuclear powers.

Strategic Arms Limitation Talks I (SALT I) - 1969-1972
Strategic Arms Limitation Talks between the United States and the Soviet Union sought to limit and restrain land- and submarine-based offensive nuclear weapons. The talks, riddled with diplomatic and political obstacles, dragged on from November 1969 to May 1972. Efforts to limit the strategic nuclear arms were difficult given that the United States possessed far more warheads than the Soviets. This made it difficult to equate the number, type or categories of weapons and to define overall strategic equivalence.

The Soviets, hoping to continue to build up its nuclear arms stockpile, sought to restrict negotiations to only banning anti-ballistic missile systems. The United States argued that to do so would be incompatible with the basic objectives of talks aimed at limiting strategic arms. Finally the deadlock was resolved when both sides agreed to concentrate on a permanent treaty to limit ABM systems, but at the same time to work out certain limits on offensive systems and establish a second round of SALT negotiations to reach a more comprehensive and long-term agreement.

The first round of SALT concluded with the signing of a five-year Interim Agreement to limit further construction of intercontinental missile sites and other nuclear systems and the signing of the Anti-Ballistic Missile Treaty.

Anti-Ballistic Missile Treaty - 1972
The ABM, signed in Moscow on May 26, 1972 was the first real nuclear-related agreement between the United States and the former Soviet Union. The treaty on the Limitation of Anti-Ballistic Missile Systems restricted the development of a defensive missile system that would prevent the penetration of others' retaliatory missiles. The United States and the Soviet Union agreed that each would have only two deployment areas, one to protect the capital and another at a major missile base. The sites would be at least 807 miles apart and the ABM deployment systems would be limited to no more than 100 interceptor missiles and 100 launchers at each site. The treaty has subsequently undergone extensive modifications.

In December 2001 the United States pulled out of the 1972 ABM Treaty following months of talks to persuade Russia to set aside the treaty and negotiate a new strategic agreement.

Strategic Arms Limitation Talks II (SALT II) - 1972-1979
The second round of Strategic Arms Limitation Talks, which opened in November 1972, aimed to replace the five-year Interim Agreement with a more comprehensive long-term treaty to limit the number and types of nuclear missiles.

The two sides remained far apart in the negotiations until a summit between American President Gerald Ford and Soviet General Secretary Leonid Brezhnev in 1974 in Vladivostok during which the parties reached a basic framework for an agreement. But, despite the framework, negotiations bogged down over the limitations on American cruise missiles and the Soviet "Backfire"-class bombers.

		AP President Bush announces the United States will withdraw from the 1972 ABM Treaty.

The American government reinvigorated the stalled talks after Jimmy Carter became president in 1977. At that time, the United States put forward two proposals, one a much more sweeping set of weapons limitations and the other an agreement similar to the Vladivostok accord, with the cruise missiles and Backfire issues deferred until later negotiations. The Soviet Union rejected both the proposals.

After further negotiations both sides agreed to a framework that accommodated the Soviets' desire to retain the Vladivostok framework, and the U.S. desire for more comprehensive limitations on SALT II. A final agreement was signed on June 18, 1979 but expired in 1985 without either side formally implementing the pact.

Threshold Test Ban Treaty - 1974
Despite the prolonged and ultimately unsuccessful SALT II work, Brezhnev and President Ford did reach an agreement during the 1974 summit to scale back the giant, thermonuclear tests taking place. The treaty prohibited underground nuclear weapons testing exceeding 150 kilotons, far smaller than many of the tests taking place in the 1960s and early '70s. In addition, the treaty required both nations to share much of the data learned from future tests.

By the time the United States submitted the treaty to the Senate for approval, the Soviets and American negotiators had also reached an agreement on further limits to underground nuclear testing.

Although formal negotiations would drag on for years and the final treaties did not enter into force until 1990, both nations informally agreed to observe the treaty limitations starting in 1976.

Intermediate-range Nuclear Forces Treaty - 1987
The Soviets and Americans crossed a major threshold when President Ronald Reagan and Soviet Premier Mikhail Gorbachev signed the Intermediate-range Nuclear Forces Treaty on December 8, 1987. The pact marked the first time the two major powers had agreed to reduce the number of nuclear missiles in its arsenal, rather than set a ceiling the two sides would not exceed in the future. The treaty focused on the ground-launched ballistic and cruise missiles with ranges of about 300 to 3,400 miles based mostly in Europe.

The Soviets, who had recently upgraded their shorter ranger missiles when talks opened in 1981, initially opposed full-scale elimination of the missiles, instead proposing a cap of 300 such missiles. NATO and the Americans wanted to fully dismantle the missiles and these talks ended in a Soviet walk-out in late 1983.

Talks resumed in 1985 and then at a 1986 summit between Gorbachev and President Reagan in Reykjavik, Iceland, the two sides reached a tentative deal. Within months the final details were hammered out and the final accord signed. Both nations fully ratified the treaty in May 1988.

Strategic Arms Reduction Treaty (START I) - July 31, 1991
The Strategic Arms Reduction Treaty, signed by President George H.W. Bush and Soviet leader Mikhail Gorbachev on July 31, 1991, was the most sweeping arms reduction treaty ever entered into by the two great nuclear superpowers. The result of nearly a decade of difficult negotiation, the treaty required the United States and Soviet Union to reduce their strategic nuclear forces.

With the reductions, each nation would still control:

• 1,600 Strategic Nuclear Delivery Vehicles -- that is the sum of all inter-continental ballistic missiles, submarine-launched missiles and deployed heavy bombers
• 6,000 nuclear warheads of which no more than 4,900 could be on ballistic missiles.
• No more than 1,100 nuclear missiles deployed on mobile launchers

The agreement also limited the development of new and more deadly missile systems and established a wide-ranging inspection regime to ensure the treaty was adhered to by both sides.

When the Soviet Union dissolved in 1991, the START limits appeared to be in danger, but negotiators from the United States and the four nations that inherited the Soviet's nuclear force -- Russia, Ukraine, Kazakhstan and Belarus -- negotiated an additional protocol where Russia would take control of the nuclear arms and abide by the START pact and the other three nations would declare themselves non-nuclear states and agree to the nuclear Non-Proliferation Treaty.

On Dec. 5, 2001 the United States and the Russian Federation successfully reached START levels of 6,000 warheads completing the largest arms control reductions in history.

Strategic Arms Reduction Treaty (START II) - 1993
Built on the foundations of the START agreement, the Russian and American governments negotiated a second treaty to further reduce nuclear stockpiles by roughly two-thirds compared to pre-START levels. President George H.W. Bush and Russian President Boris Yeltsin signed the Treaty Between the United States of America and the Russian Federation on Further Reduction and Limitation of Strategic Offensive Arms, or START II for short, on Jan. 3, 1993.

		Paul Morse President Bush and Russian President Putin sign an arms reduction treaty in Moscow in 2002.

The pact, approved by the U.S. Senate in 1996 and the Russian Duma in 2000, set in place a two-phased reduction in nuclear weapons systems. The main thrust of this effort was to eliminate the larger Intercontinental Ballistic Missiles (ICBMs) and the rockets that carried multiple warheads, technically known as Multiple-Reentry Vehicles (MRVs).

In Phase One -- set to be complete by 2001 -- each side must have reduced its total deployed strategic nuclear warheads to 3,800-4,250. Of those warheads, no more than 1,200 may be on deployed MRVs, no more than 2,160 may be on deployed submarines, and no more than 650 may be on deployed heavy ICBMs.

In Phase Two -- set to be complete by 2007 -- each side must have reduced its total deployed strategic nuclear warheads to 3,000-3,500. Of those, none may be on land-based MRVs. No more than 1,700-1,750 deployed warheads may be on submarines.

Comprehensive Test Ban Treaty - 1996
It took the end of the Cold War to usher in serious negotiations about a global ban on nuclear testing. Negotiations began in 1991 when the nations that had signed on to the Partial Test Ban Treaty hosted talks aimed at creating a more complete ban. The treaty that emerged from years of negotiation received the overwhelming support of the United Nations General Assembly in 1996 and was then signed by 71 nations, including France, the United Kingdom, China, the United States and the Russian Federation.

Quite simply, the treaty prohibits states from detonating any nuclear explosion, whether for weapons testing or for peaceful research purposes. It also establishes an organization to oversee the ban and verify nations are complying with the treaty obligations.

The treaty cannot come into force unless 44 countries with nuclear capabilities sign it. To date, 41 have signed and 33 have ratified the treaty. Non-signatories include India, Pakistan and North Korea. In addition, 13 nations have signed the accord but not officially ratified it, including the United States and China. The U.S. Senate took up the treaty in 1999, but voted 51-48 to reject it, although it left open the possibility of taking the pact back up at a later date.

Despite the delay in the treaty entering into force, the Preparatory Commission for the CTBT Organization has already been formed to begin readying the implementation of the treaty once the 44th state has signed.

Treaty of Moscow - 2002
Signed by the United States and Russia on May 26, 2002, the treaty called for both sides to reduce their nuclear warheads from 6,000 to 2,200 by the year 2012. Once ratified, the new treaty will replace the START II treaty. Despite this agreement, both Russia and America have said they will continue to invest in modernizing the remaining forces. Additionally, both nations have said the additional warheads will be placed in storage rather than dismantled.

-- Compiled by Wendy Mbekelu for the Online NewsHour