By Alicia Sanders-Zakre
March 6: U.S. Secretary of State Clinton presents “reset button” to Russian Foreign Minister Lavrov, symbolizing an effort to improve relations.
April 5: President Obama in Prague outlines his plan for nuclear risk reduction and nonproliferation, calling on countries to have “the courage to pursue a world without nuclear weapons.”
April 8: Obama administration announces it will participate in multilateral talks with Iran on its nuclear program, a departure from previous U.S. policy.
May 25: North Korea conducts second nuclear test explosion.
June 12: UN Security Council passes Resolution 1874, adding sanctions on North Korea for its nuclear and missile activities.
September 25: The United States, the U.K. and France reveal that Iran has been constructing a secret, second uranium-enrichment facility, Fordow.
April 6: Pentagon releases 2010 “Nuclear Posture Review” report,” which outlines a diminished role for nuclear weapons and a “no new nuclear weapons policy,” but calls for maintaining robust nuclear deterrent.
April 8: Obama and Russian President Medvedev sign the New Strategic Arms Reduction Treaty (New START), which limits each side to no more than 1,550 strategic deployed warheads by 2018.
April 12-13: First nuclear security summit involving 47 states is held in Washington to consolidate and protect nuclear material.
May 13: Obama announces plan to modernize U.S. nuclear forces.
May 28: Eighth nuclear Nonproliferation Treaty (NPT) Review Conference adopts 64-point action plan by consensus.
December 22: U.S. Senate approves ratification of New START by vote of 71-26.
January 12: U.S.-Russia 123 agreement for cooperation on the peaceful uses of nuclear energy enters into force.
June 2: 46-nation Nuclear Suppliers Group adopts tougher guidelines to prevent the spread of enrichment and reprocessing technology.
July 13: U.S.-Russia agreement to dispose of excess weapons-grade plutonium enters into force.
February 29: North Korea accepts “Leap Day agreement” for nuclear constraints with U.S. providing food aid. The deal collapses in April 2012.
March 26-27: Second nuclear security summit is held in Seoul; expands scope to address radioactive sources and nuclear safety.
August 20: Obama says use or “moving around” of chemical weapons by Syrian government would cross a “redline.”
January 4: UN General Assembly votes to convene an open-ended working group to develop proposals for multilateral nuclear disarmament.
January 22: UN Security Council adopts Resolution 2087 against North Korea after successful Dec. 12 satellite launch.
February 12: North Korea conducts third nuclear test explosion.
March 7: UN Security Council adopts Resolution 2094 in response to North Korea’s nuclear and missile activities.
April 2: UN General Assembly approves text of global Arms Trade Treaty 156-3-23.
June 19: Obama calls for U.S.-Russian talks to reduce deployed strategic nuclear weapons by as much as one-third below New START levels.
August 21: Chemical weapons attack by the Syrian government in Ghouta kills 1,400 people.
September 23: United States becomes 91st state to sign the Arms Trade Treaty.
September 27: Obama and Iranian President Rouhani have first direct talks between U.S. and Iranian leaders since the 1979 revolution.
November 24: Six world powers and Iran conclude the Joint Plan of Action, an interim agreement freezing Iran’s nuclear progress and guide negotiations for a comprehesive solution.
March 24-25: Third nuclear security summit held in the Netherlands.
July 31: United States reports that Russia is in violation of the 1987 Intermediate-Range Nuclear Forces Treaty.
September 4: Joint mission of the Organisation for the Prohibition of Chemical Weapons (OPCW) and the United Nations declares it has removed 96 percent of Syria’s chemical weapons, including precursor chemicals.
December 4: United States announces International Partnership for Nuclear Disarmament Verification.
April 27 - May 22: Ninth NPT Review Conference fails to produce a final agreement.
May 27: Obama becomes first sitting U.S. president to visit Hiroshima, Japan.
July 14: Iran and P5+1 countries announce the JCPOA to verifiably roll back Iran’s nuclear program over a multi-year period.
August 7: UN Security Council authorizes Joint Investigative Mechanism to identify individuals and groups using chemical weapons in Syria.
September 10-11: Resolution of disapproval fails to block the JCPOA fall short of necessary votes in the Senate and U.S. House of Representatives.
October 29: UN General Assembly votes to convene an open-ended working group to address concrete, effective legal measures to attain a world without nuclear weapons.
January 6: North Korea conducts fourth nuclear test explosion.
January 16: Implementation day for the Joint Comprehensive Plan of Action.
March 2: UN Security Council unanimously adopts Resolution 2270 against North Korea following nuclear tests and prohibited satellite launch.
March 31 - April 1: Fourth and final nuclear security summit is held in Washington; states designate five international organizations as successors for summit work.
August 24: UN Security Council panel finds that Syrian government troops were responsible for two toxic gas attacks and that Islamic State militants used sulfur mustard gas.
August 27: OPCW reports all chemical weapons have been removed from Libya.
September 9: North Korea conducts fifth nuclear test explosion.
September 23: UN Security Council adopts Resolution 2310 reaffirming support for the moratoria on nuclear weapons testing 20 years after the Comprehensive Test Ban Treaty was opened for signature.
October 5: Russia suspends agreement with U.S on nuclear and energy-related research cooperation.
October 27: UN General Assembly passes resolution to begin negotiations in 2017 on a treaty to prohibit nuclear weapons.