June 17, 1925 -- The "Protocol for the Prohibition of the Use in War of Asphyxiating, Poisoning or other Gases, and Bacteriological Methods of Warfare" (The Geneva Protocol) is signed.

July 16, 1945 -- The U.S. conducts the world's first nuclear test at Alamagordo Air base, New Mexico.

June 14, 1946 -- The U.S. presents the Baruch Plan for the international control of atomic energy. It called for the establishment of an international authority to control potentially dangerous atomic activities, license all other atomic activities, and carry out inspections.

November 1949 -- The U.S. and six Western European nations create the Coordinating Committee for Multilateral Export Controls (COCOM) to prevent the transfer of militarily useful technology to the communist world.

December 8, 1952 -- The U.S. presents an "Atoms for Peace" plan that leads to the creation of the International Atomic Energy Agency (IAEA) in 1957.

April 16, 1953 -- U.S. President Dwight D. Eisenhower proposes that nations limit the portion of total production of strategic materials devoted to military purposes in his "Chance for Peace" speech.

April 2, 1954 -- Indian Prime Minister Jawaharlal Nehru is the first to propose a "standstill agreement" on nuclear testing.

August 30, 1954 -- President Eisenhower signs the Atomic Energy Act of 1954, which authorizes the exchange of information for the peaceful use of atomic energy with other countries and supports the development of commercial nuclear power.

July 21, 1955 -- President Eisenhower presents his "Open Skies" plan, designed to protect nations against military buildup and surprise attack.

August 29, 1957 -- Following consultations among the NATO allies and other nations, the West presents to the United Nations a working paper entitled "Proposals for Partial Measures of Disarmament," intended as "a practical, workable plan to start on world disarmament." The plan would stop all nuclear testing, halt production of nuclear weapons materials, start a reduction in nuclear weapons stockpiles, reduce the danger of surprise attack through warning systems, and begin reductions in armed forces and armaments.

July 1, 1958 -- A Conference of Experts, proposed by President Eisenhower, convenes in Geneva, bringing together scientists from the U.S., Britain, the Soviet Union, France, Canada, Czechoslovakia, Romania, and Poland to examine nuclear test ban verification issues. The experts' report concludes that a Comprehensive Test Ban (CTB) in the atmosphere, underground and underwater can be verified by use of some 160 monitoring stations around the world. Nuclear tests beyond 50 kilometers from Earth would escape detection by existing technology.

October 31, 1958 -- The U.S., the Soviet Union, and Britain begin the Geneva Conference on the Discontinuance of Nuclear Weapon Tests, as proposed by President Eisenhower. Within a few days, the Soviet Union joins the U.S. and Britain in a one-year testing moratorium.

December 1, 1959 -- The U.S., the Soviet Union, and 10 other countries sign a treaty to internationalize and demilitarize the Antarctic continent. It entered into force on June 23, 1961.

February 13, 1960 -- France explodes its first nuclear device at a test site in the Sahara Desert.

May 2, 1960 -- After a U.S. U-2 reconnaissance plane is shot down over Sverdlovsk, Soviet Premier Nikita Khrushchev cancels the "Big Four" Paris Summit, halting seeming progress in test ban negotiations. Negotiations reconvene in March 1961.

September 1, 1961 -- Citing French tests and the tensions created by the Berlin crisis, the Soviet Union announces plans to resume testing.

June 20, 1963 -- In the aftermath of the Cuban missile crisis, the U.S. and the Soviet Union sign a Memorandum of Understanding in Geneva to establish a direct "hotline" communications link between the two nations for use in a crisis.

August 5, 1963 -- The U.S., Britain, and the Soviet Union sign the Limited Test Ban Treaty, barring nuclear testing in the atmosphere, underwater, and in outer space. It entered into force October 10.

October 16, 1964 -- China explodes its first nuclear weapon at Lop Nor on the Qinghai Plateau.

February 14, 1967 -- The Regional Treaty for the Prohibition of Nuclear Weapons in Latin America -- the Treaty of Tlatelolco -- is signed in Mexico City. The treaty entered into force on April 22, 1968.

July 1, 1968 -- The U.S. and 61 other nations sign the Nuclear Non-Proliferation Treaty (NPT) obliging states without nuclear weapons at the time not to make or acquire such weapons, and requiring all parties to pursue negotiations on arms control and disarmament. It was extended indefinitely on May 11, 1995.

November 17, 1969 -- The U.S. and the Soviet Union open the Strategic Arms Limitation Talks (SALT I) in Helsinki to discuss limits on both strategic nuclear offensive weapons and anti-ballistic missile (ABM) systems.

November 25, 1969 -- The U.S. renounces the first use of chemical weapons and all methods of biological warfare.

March 1971 -- The Nuclear Non-Proliferation Treaty Exporters Committee, known as the Zangger Committee, is established as the first major international effort to develop export controls on nuclear materials.

March 5, 1970 -- The NPT enters into force.

September 30, 1971 -- The U.S. and the Soviet Union sign an Agreement on Measures to Reduce the Risk of Outbreak of Nuclear War.

April 10, 1972 -- The U.S. signs the Biological and Toxin Weapons Convention (BWC), which bans the development, production, testing and transfer of microbial and toxin agents for offensive military purposes.

May 26, 1972 -- President Nixon and Soviet General Secretary Leonid Brezhnev sign in Moscow the basic SALT I documents limiting strategic offensive arms; both enter into effect on October 3 of that year. SALT I expired in October 1977.

May 26, 1972 -- The U.S. and the Soviet Union sign the Anti-Ballistic Missile (ABM) Treaty limiting strategic anti-ballistic missile defenses.

May 18, 1974 -- India conducts its only nuclear test at an underground test site in the Rajasthan Desert.

July 3, 1974 -- The Threshold Test Ban Treaty is signed, prohibiting underground nuclear weapon tests of more than 150 kilotons and obliging parties to continue negotiations toward a Comprehensive Test Ban. The treaty entered into force on December 11, 1990.

July 3, 1974 -- The U.S. and the Soviet Union sign a protocol reducing the number of ABM deployment areas permitted for each side from two to one.

January 22, 1975 -- The U.S. ratifies the Geneva Protocol banning use of chemical and bacteriological weapons, which it originally signed in 1925.

August 1, 1975 -- The U.S., the Soviet Union, and 33 other member states of the Conference on Security and Cooperation in Europe (CSCE) sign the Helsinki Final Act. The document initiates a series of agreements on confidence- and security-building measures in Europe.

May 28, 1976 -- The Peaceful Nuclear Explosions Treaty is signed, limiting the size of individual nuclear explosions to a yield of 150 kilotons. U.S. President Gerald Ford delays ratification of both this treaty and the earlier Threshold Test Ban Treaty.

June 18, 1979 -- The U.S. and the Soviet Union sign the SALT II Treaty in Vienna, replacing SALT I. The SALT II Treaty was never ratified.

December 27, 1979 -- Following the Soviet invasion of Afghanistan, President Carter withdraws the SALT II Treaty from Senate consideration.

October 1980 -- Preliminary Intermediate-range Nuclear Forces (INF) talks between the U.S. and the Soviet Union begin in Geneva. The U.S. opening position calls for an equal ceiling on land-based theater nuclear missile systems.

October 16, 1980 -- China conducts its last atmospheric nuclear test.

March 23, 1983 -- U.S. President Ronald Reagan announces his intention to commit the U.S. to a research program to study the feasibility of defensive measures against ballistic missiles to maintain peace. The program becomes known as the Strategic Defense Initiative (SDI).

October 27, 1983 -- The U.S. and its allies agree to maintain NATO's nuclear capability at the lowest level consistent with security and deterrence, and to withdraw 1,400 U.S. nuclear warheads from Europe.

April 1984 -- The U.S. signs a nuclear trade pact with China after Beijing agrees to join the IAEA and accept IAEA inspection of any exported nuclear equipment and material.

June 1985 -- In reaction to the use of chemical weapons in the Iran-Iraq War, the U.S., Canada, Japan, New Zealand, Australia and the 10 European Community countries establish the Australia Group to develop a system of export controls on precursor chemicals required to manufacture chemical weapons.

August 6, 1985 -- Eight members of the South Pacific Forum sign the South Pacific Nuclear-Free Zone Treaty, or the Raratonga Treaty, establishing a nuclear-free zone in the southern Pacific.

December 12, 1985 -- North Korea formally accedes to the NPT and agrees to open a new 30-megawatt research reactor facility to IAEA inspections and safeguards.

September 22, 1986 -- The Conference on Confidence- and Security-Building Measures and Disarmament in Europe adopts an accord, the Stockholm Document, designed to reduce the risk of war in Europe. NATO and Warsaw Pact member nations agree to give each other advance notice of all major military activities.

April 7, 1987 -- The Missile Technology Control Regime (MTCR) is established to slow the spread of missiles capable of delivering weapons of mass destruction.

December 8, 1987 -- The U.S. and the Soviet Union sign the INF Treaty to eliminate all intermediate- and short-range land-based nuclear missiles, the first arms control agreement to eliminate an entire class of nuclear weapons. It features an extensive and comprehensive verification regime, including on-site inspections. The treaty entered into force June 1, 1988, and was fully implemented June 1, 1991.

The first U.S. Pershing missile engine is destroyed in Texas in 1995 under the terms of the 1987 Intermediate-Range Nuclear Forces Treaty.

U.S. Air Force photo by TSGT Tomoyasu.

December 9, 1987 -- The U.S. and the Soviet Union agree to conduct the Joint Verification Experiment, allowing each side to monitor a nuclear test conducted by the other. The Soviet Union monitors a test August 17, 1988, and the U.S. on September 14 of the same year.

January 26, 1988 -- The U.S. On-Site Inspection Agency (OSIA) is established to carry out the on-site inspection, escort, and monitoring provisions of the INF Treaty. It later becomes responsible for the U.S. inspection activities required under other major arms control agreements.

June/July 1988 -- The U.S. and the Soviet Union hold the first session of the Special Verification Commission (SVC) for the INF Treaty in Geneva. The SVC resolves INF Treaty compliance questions and agrees upon measures necessary to improve the viability and effectiveness of the treaty.

May 12, 1989 -- President Bush renews and expands upon President Eisenhower's 1955 "Open Skies" proposal and invites the Soviet Union and other members of the Warsaw Pact and NATO to agree to unarmed surveillance flights over their territories.

June 12, 1989 -- The U.S. and the Soviet Union sign the Dangerous Military Activities Agreement, which commits both nations to seek to prevent four types of dangerous military activities during peacetime: unintentional or emergency entry into the national territory of the other side, hazardous use of laser devices, disruption of military operations in a mutually agreed upon "Special Caution Area," and interference with the command and control networks of either side.

May 22, 1990 -- President Bush signs the Biological Weapons Anti-Terrorism Act, making it illegal for the U.S. to develop or possess biological weapons.

June 1, 1990 -- The U.S. and the Soviet Union sign new verification protocols for the Threshold and Peaceful Explosions Treaties. They entered into force on December 11, 1990.

June 1, 1990 -- Presidents Bush and Gorbachev sign the bilateral "Agreement on Destruction and Non-production of Chemical Weapons and on Measures to Facilitate the Multilateral Convention on Banning Chemical Weapons."

October 24, 1990 -- The Soviet Union conducts its last nuclear test before adhering to a unilateral moratorium.

November 17, 1990 -- The U.S. and other member countries of the Conference on Security and Cooperation in Europe agree to the Vienna Document 1990, which expands and improves upon the notification measures and information exchanges in the 1986 Stockholm Document. It also establishes a Conflict Prevention Center in Vienna.

November 19, 1990 -- The U.S. and 21 other NATO and Warsaw Pact nations sign the Conventional Armed Forces in Europe (CFE) Treaty, reducing five categories of conventional weapons to equal levels for each alliance grouping. The treaty entered into force July 17, 1992.

April 3, 1991 -- The U.N. Security Council passes Resolution 687 requiring the destruction of Iraq's nuclear capability, as well as its chemical and biological weapons, and of missiles with a range over 150 kilometers. The council establishes a Special Commission to monitor the elimination of weapons of mass destruction in Iraq.

May 28, 1991 -- President Bush announces an arms control plan for the Middle East that includes a ban on weapons of mass destruction and a freeze on the acquisition, production, and testing of surface-to-surface missiles.

July 10, 1991 -- South Africa formally joins the NPT as a non-nuclear state.

July 31, 1991 -- U.S. and Russia sign the Strategic Arms Reduction Treaty (START I), cutting their long-range nuclear forces from a Cold War high of between 11,000 and 12,000 warheads to between 6,000 and 7,000 for each side. The treaty entered into force on December 5, 1994.

Ukrainian Army personnel oversee the removal of an SS-19 ICBM from its underground silo in Pervomaysk preparatory to destroying it under the provisions of the 1991 Strategic Arms Reduction Treaty.

Department of Defense photo by R.D. Ward.

September 27, 1991 -- President Bush announces the unilateral U.S. withdrawal from overseas bases and operational deployment of all land- and sea-based tactical nuclear weapons.

October 5, 1991 -- President Gorbachev, in response to President Bush's initiative, announces that the Soviet Union will immediately: stand down all strategic bombers currently on day-to-day alert status and store their weapons; stand down 503 ICBMs; stop the buildup of launching facilities for rail-based ICBMs; and discontinue development of small, mobile ICBMs and of a short-range attack missile for heavy bombers.

November 27, 1991 -- The U.S. Congress passes the Nunn-Lugar legislation (formally known as the Soviet Nuclear Threat Reduction Act) to help the Soviet Union destroy nuclear, chemical, and other weapons. President Bush signs it in December, approving the first $400 million in aid to the Commonwealth of Independent States (CIS).

December 1991 -- The U.N. General Assembly votes to formally establish a Register of Conventional Arms. Beginning April 30, 1993, the U.N. will maintain a register to which states voluntarily report their arms exports and imports in seven major categories of weapons.

January 20, 1992 -- North and South Korea agree to denuclearize the Korean Peninsula.

March 9, 1992 -- China becomes the fourth nuclear weapon state to accede to the NPT.

March 24, 1992 -- The Open Skies Treaty is signed during a meeting of the CSCE in Helsinki.

May 23, 1992 -- The U.S., Belarus, Kazakstan, Russia, and Ukraine sign the Lisbon START Protocol under which all five countries become parties to START and the CIS states agree to join the NPT as non-nuclear-weapon states.

August 3, 1992 -- France, the last of five acknowledged nuclear weapon states, joins the NPT.

September 23, 1992 -- The U.S. conducts its last nuclear test.

October 9, 1992 -- The CIS states sign the Bishkek Agreement pledging to support and implement the ABM Treaty.

October 22-23, 1992 -- Belarus agrees to transfer its nuclear missiles to Russia.

January 3, 1993 -- U.S. and Russia sign the START II Treaty to further reduce intercontinental ballistic missiles (ICBMs) by eliminating MIRVed (multiple independently targetable re-entry vehicle) ICBMs and cutting the number of overall warheads for each side to between 3,000 and 3,500.

January 13, 1993 -- The United States signs the Chemical Weapons Convention (CWC). As of June 11, 1997, 95 nations, including the U.S., had ratified the convention.

March 1993 -- North Korea refuses to accept a special IAEA inspection team, and subsequently announces its decision to withdraw from the NPT.

July 22, 1993 -- Belarus formally accedes to the NPT and signs three agreements with the U.S. releasing Nunn-Lugar funding for denuclearization assistance.

November 17, 1993 -- In view of the changed security environment, the 17 COCOM members agree to abolish the organization and start a new, broader one.

December 16, 1993 -- The U.N. General Assembly approves by consensus resolution 48/70 supporting the multilateral negotiation of the CTBT (Comprehensive Test Ban Treaty). This is the first time that a consensus resolution in support of a CTBT has been adopted by the assembly.

January 14, 1994 -- The United States, Russia, and Ukraine sign the Trilateral Statement, providing for the transfer of strategic nuclear warheads on Ukrainian territory back to Russia. The transfer is completed by June 1996.

June 23, 1994 -- U.S. Vice President Al Gore and Russian Prime Minister Viktor Chernomyrdin sign an agreement to shut down by the year 2000 the remaining plutonium production reactors operating in Russia.

October 23, 1994 -- The United States and the Democratic People's Republic of Korea (DPRK) sign an "Agreed Framework" to freeze the North Korean nuclear program and halt the DPRK's withdrawal from the Nuclear Non-Proliferation Treaty.

December 5, 1994 -- Ukraine accedes to the NPT as a non-nuclear weapon state.

May 12, 1995 -- The Nuclear Non-Proliferation Treaty is extended indefinitely.

June 13, 1995 -- French President Jacques Chirac announces that France will resume nuclear testing in September with a series of eight tests in the South Pacific to last until May 1996. Two months later, in the face of negative reaction, France announces the tests will end more quickly.

August 11, 1995 -- President Clinton announces that the U.S. will support a true zero-yield CTBT banning any nuclear weapon test explosion or any other nuclear explosion.

November 17, 1995 -- Equipment reductions are completed under the CFE Treaty and its limits take full effect.

December 15, 1995 -- ASEAN, joined by Cambodia, Laos, and Burma, approves the creation of the Southeast Asian Nuclear-Weapon-Free Zone.

December 19, 1995 -- The U.S. and 27 nations establish the "Wassenaar Arrangement on Export Controls for Conventional Arms and Dual-Use Goods and Technologies" as a successor to the COCOM, to devise new international controls on the spread of dangerous military technologies.

January 26, 1996 -- U.S. Senate ratifies START II; the treaty awaits ratification by the Russian Duma.

January 27, 1996 -- France conducts its sixth and final nuclear test. Five days later, President Chirac announces that France has finished testing "once and for all" and states that he is prepared to push for completion of a zero-yield CTBT in 1996.

March 25, 1996 -- The U.S. signs the protocols to the South Pacific Nuclear-Free Zone Treaty obligating the U.S. not to manufacture, acquire, test, or station any nuclear explosive device in the South Pacific.

April 11, 1996 -- Forty-three African nations sign the Pelindaba Treaty establishing a nuclear-weapon-free zone in Africa.

May 16, 1996 -- President Clinton announces U.S. anti-personnel landmine (APL) policy, calling for a worldwide ban on production, transfer, and use of anti-personnel landmines.

June 20, 1996 -- India announces it will not sign the CTBT as drafted because it would still permit the nuclear weapon states to "continue refining and developing their nuclear arsenal."

September 10, 1996 -- The U.N. General Assembly reconvenes and votes to adopt the CTBT and open it for signature at the earliest possible date. India, Bhutan, and Libya voted against, while Cuba, Lebanon, Syria, Mauritius, and Tanzania abstained.

September 24, 1996 -- President Clinton is the first head of state to sign the CTBT. He is followed by the other four declared nuclear powers and a host of non-nuclear states.

January 17, 1997 -- President Clinton declares that the U.S. will pursue a comprehensive, global ban on anti-personnel landmines through the Conference on Disarmament in Geneva and a permanent ban on APL export and transfer, as well as establish a stockpile cap at current inventory levels.

April 24, 1997 -- U.S. Senate ratifies the Chemical Weapons Convention.

April 29, 1997 -- Chemical Weapons Convention enters into force.

June 26, 1997 -- The Conference on Disarmament approves a proposal to appoint a special coordinator who will seek to develop a mandate for negotiations on anti-personnel landmines and names Australian Ambassador John Campbell to the post.