(CNN) -- Here's a look at what you need to know about North Korea's nuclear capabilities and history.
1985 North Korea joins the Nuclear Non-Proliferation Treaty (NPT).
1993 International Atomic Energy Agency (IAEA) charges that North Korea is violating the NPT and demands that inspectors be given access to two nuclear waste storage sites.
North Korea threatens to quit the Nuclear Nonproliferation Treaty amid suspicions that it is developing nuclear weapons. It ultimately does not quit the program but agrees to inspections in 1994.
1994 North Korea and U.S. sign an agreement. North Korea pledges to freeze and eventually dismantle its nuclear weapons program in exchange for international aid to build two power-producing nuclear reactors.
1998 August 31 - North Korea fires a multistage rocket that flies over Japan and lands in the Pacific Ocean, proving the North Koreans can strike any part of Japan's territory.
November 17 - The U.S. and North Korea hold the first round of high-level talks in Pyongyang over North Korea's suspected construction of an underground nuclear facility. The United States demands inspections.
1999 February 27-March 16 - During a fourth round of talks, North Korea allows U.S. access to the site in exchange for U.S. aid in increasing North Korean potato yields. U.S. inspectors find no evidence of any nuclear activity during a visit to site in May.
September 13 - North Korea agrees to freeze testing of long-range missiles while negotiations with the U.S. continue.
September 17 - President Bill Clinton agrees to ease economic sanctions against North Korea.
December - A U.S.-led international consortium signs a $4.6 billion contract to build two nuclear reactors in North Korea.
2000 July - North Korea threatens to restart its nuclear program if the U.S. does not compensate it for the loss of electricity caused by delays in building nuclear power plants.
2001 June - North Korea warns it will drop its moratorium against testing missiles if the U.S. does not pursue normalized relations with North Korea. It also says it will restart its nuclear program if there is not more progress on two U.S.-sponsored nuclear power plants being built in North Korea.
2002 January 29 - President George W. Bush labels North Korea, Iran and Iraq an "axis of evil" in his State of the Union address. "By seeking weapons of mass destruction, these regimes pose a grave and growing danger," he says.
October 4 - U.S. officials, in closed talks, confront North Korea with evidence that they are operating a nuclear weapons program in violation of the 1994 nuclear agreement. Specifically, the U.S. has proof that they are operating a uranium enrichment facility. North Korea admits that is has been operating the facility in violation of the agreement. The information is NOT made public.
October 16 - The Bush Administration first reveals that North Korea has admitted operating a secret nuclear weapons program in violation of the 1994 agreement. They have NOT, apparently, admitted having any nuclear weapons.
December 22 - North Korea says it has begun removing IAEA monitoring equipment from nuclear facilities.
December 31 - North Korea expels IAEA inspectors.
2003 January 10 - North Korea withdraws from the Nuclear Nonproliferation Treaty.
February 5 - North Korea's official news agency says the nation has reactivated its nuclear power facilities.
February 24 - North Korea test fires a land-to-ship missile into the sea between the Korean Peninsula and Japan.
February 26 - The United States says North Korea has reactivated its five-megawatt nuclear reactor at Yongbyon.
March 10 - North Korea test fires another surface-to-vessel anti-ship missile into the Sea of Japan.
April 23, 2003 - Declares it has nuclear weapons.
August 27 - The U.S., North Korea, South Korea, China, Japan and Russia take part in talks about the crisis in North Korea.
2004 February 24-28 - The U.S., North Korea, South Korea, China, Japan and Russia meet in Beijing, China for more talks. The summit closes with no major progress but with an agreement for more talks.
June - The six nations meet again in Beijing for more talks.
August 2004 - North Korea offers to freeze its nuclear program in exchange for aid, easing of sanctions and being removed from the US's list of state sponsors of terrorism. The U.S. wants North Korea to disclose all nuclear activities and allow inspections.
2005 February 10 - North Korea drops out of six-party nuclear talks and says it will bolster its nuclear weapons arsenal. North Korea insists on a bilateral non-aggression pact with the U.S. before it will consider dismantling its nuclear program. The U.S. insists Pyongyang must first agree to permanently and verifiably dismantle its nuclear weapons program before it will grant any incentives, including economic assistance and diplomatic recognition.
August 7 - After meeting for 13 straight days, diplomats from the United States, North Korea and four other Asia-region powers decide to take a recess from talks aimed at getting North Korea to dismantle its nuclear program.
September 13 - The six-party talks resume in Beijing.
September 19 - North Korea agrees to give up its entire nuclear program, including weapons, a joint statement from six-party nuclear arms talks in Beijing said. "The Democratic People's Republic of Korea (North Korea) committed to abandoning all nuclear weapons and existing nuclear programs and returning at an early date to the treaty on the nonproliferation of nuclear weapons (NPT) and to IAEA (International Atomic Energy Agency) safeguards," the statement said. - In exchange, the U.S., China, Japan, Russian and South Korea have "stated their willingness" to provide energy assistance to North Korea, as well as promote economic cooperation. - North Korean officials later state that their country would begin dismantling its nuclear program only if the U.S. provides a light-water reactor for civilian power -- a demand that could threaten a day-old agreement among North Korea, its neighbors and the United States.
"Without this physical guarantee of the (light-water reactor), our position is not to even dream of us giving up our nuclear deterrence."
2006 July 4 - North Korea test-launches a Taepodong-2 missile along with two short-range rockets, but the long-range missile apparently fails.
July 15 - The UN Security Council unanimously passes a resolution demanding that North Korea suspend its missile program. The North Korean ambassador immediately rejects the resolution.
October 9 - North Korea claims to have successfully tested a nuclear weapon. The supposed test is conducted at an underground facility in Hwaderi near Kilju city. Though the nature of the blast as nuclear remains unconfirmed, South Korea's geology research center detects an artificial earthquake in the region of the test, and world leaders condemn North Korea's actions (test conducted at 10:36 am local time or 9:36 pm Eastern time on 10/8/2006).
October 14 - The UN Security Council approved a resolution imposing sanctions against North Korea, restricting military and luxury good trade and requiring an end to nuclear and ballistic missile tests.
October 16 - An analysis of air samples collected on October 11, 2006 detects radioactive debris, confirming North Korea's nuclear test.
2007 February 13 - North Korea agrees to close its main nuclear reactor in exchange for an aid package worth $400 million.
March 5-6 - U.S. Assistant Secretary of State Christopher Hill meets with his North Korean counterpart, Vice Foreign Minister Kim Kye Gwan, to discuss North Korea's nuclear program.
March - During six-party talks, the U.S. agrees to release approximately $25 million of North Korean funds frozen at a Macao bank, a sticking point in the negotiations. The actual release of funds does not occur until June.
June 25 - After spending two days in Pyongyang meeting with North Korea's nuclear negotiator, the U.S. Envoy to North Korea, Chris Hill, says that North Korea has reaffirmed its commitment to the nuclear disarmament agreement reached in February. He also says North Korea has invited the IAEA to monitor the shutdown of the Yongbyon nuclear facility, scheduled to occur within a few weeks.
September 2 - U.S. Assistant Secretary of State Christopher Hill announces that after talks in Geneva between U.S. and North Korean officials, North Korea has agreed to fully declare and disable its nuclear programs by the end of 2007.
September 30 - At six-party talks in Beijing, North Korea signs an agreement stating it will begin disabling its nuclear weapons facilities. North Korea also agrees to include a U.S. team of technical experts in the disabling activities.
October 2, 2007 - South Korean President Roh Moo-hyun becomes the first South Korean leader to walk across the Demilitarized Zone separating North and South Korea on his way to a three day summit with North Korean leader Kim Jong Il.
October 4, 2007 - North Korean leader Kim Jong Il and South Korean President Roh Moo-hyun sign an eight-point agreement in Pyongyang; among other things, it calls for a smooth implementation of the six-party agreements to shut down of North Korea's nuclear facilities and the replacement of North and South Korea's current armistice agreement with a permanent peace.
November 14-16, 2007 - North Korean Prime Minister Kim Yong Il and South Korean Prime Minister Han Duck-soo meet in Seoul, South Korea. At the end of the summit, they announce a number of economic projects including cross-border cargo train services, road repairs, and construction of a new industrial complex near Haeju, North Korea.
December 31 - North Korea misses a deadline to declare all its nuclear programs.
2008 January 4 - The North Korean Foreign Ministry states, via broadcast message, that North Korea had already provided enough explanation to meet the 12/31/2007 deadline, and that it had provided that information in a report presented to the U.S. in November. Members of the six party talks dispute this claim.
February 21 - After meeting with North Korean Foreign Minister Kim Kye Gwan, South Korean envoy Chun Yung Woo states that North Korea still plans to meet the obligations it agreed to during six party talks in 2007.
May 8 - An official with the U.S. State Department announces that North Korea has handed over thousands of documents pertaining to its nuclear activities, especially related to its production of plutonium, to visiting U.S. official Sohn Kim. Another official puts the number of documents at 18,000 to 19,000.
June 27 - North Korea destroys a water cooling tower at the Yongbyon facility, where officials now acknowledge they extracted plutonium to build nuclear weapons. The massive implosion is intended to be a powerful public symbol of a move to end nuclear activities by the Communist nation.
September 24 - At the request of North Korea, the IAEA removes surveillance equipment and seals from the Yongbyon nuclear facility.
October 11 - U.S. State Dept. spokesman Sear McCormack announces that North Korea has been removed from the U.S. list of states that sponsor terrorism.
October 10-17 - In response to the U.S. move, North Korea replaces the seals and surveillance equipment at its Yongbyon nuclear facility.
December 8 -11 - Another round of six-party talks is held in Beijing, China. The talks break down over North Korea's refusal to allow international inspectors unfettered access to suspected nuclear sites.
2009 January - U.S. scholar Selig Harrison meets with senior officials in North Korea. After the meeting he reports that the officials have claimed that North Korea has weaponized most of its plutonium stockpile. The amount of weaponized plutonium is allegedly enough for four to five nuclear bombs.
April 25 - North Korea announces it has begun reprocessing spent fuel rods.
May 25 - North Korea announces it has conducted its second nuclear test shortly after the U.S. Geological Survey reports a magnitude 4.7 seismic disturbance at the site of North Korea's first nuclear test. The White House is reporting that North Korea also test-fired a short range missile.
June 12 - The UN Security Council approves Resolution 1874, condemning North Korea's May 25th nuclear test. The UN also impose new sanctions, banning the sale of most arms to or from North Korea.
November 3 - North Korea's state run news agency reports that the reprocessing of 8,000 spent nuclear fuel rods has been completed. The reprocessing garnered enough weapons-grade plutonium for one to two nuclear bombs.
2010 November 20 - According to a report by Stanford University professor, Siegfried Hecker, North Korea has a new nuclear enrichment facility composed of 2,000 centrifuges. Hecker was given unprecedented access to North Korea's facility and documents.
2011 October 24 - 25 - U.S. officials, led by U.S. Ambassador Stephen Bosworth, meet with a North Korean delegation, led by First Vice Foreign Minister Kim Kye-gwan, in Geneva, Switzerland, in an effort to restart the six-party nuclear arms talks that broke down in 2008.
December 15 - U.S. and North Korean officials meet in Beijing to discuss possible food assistance to North Korea in exchange for the suspension of North Korea's uranium enrichment program.
2012 January 11 - North Korea indicates that it is open to further discussions with the U.S. over suspending its uranium enrichment program in exchange for food aid, an agreement that seemed close to realization before Kim Jong Il's death on December 17, 2011.
February 29 - The U.S. State Department announces that North Korea has agreed to a moratorium on long-range missile launches and nuclear activity at Yongbyon, the nation's major nuclear facility.
April 10 - Ryu Kun Chol, the deputy director of the Space Development Department of the Korea Space Technology Committee, outlines the country's plans to complete and launch a rocket within the next seven days. Japan, South Korea and the U.S. believe the launch to be a cover-up for testing a long-range ballistic missile.
April 13 - North Korea's long-range rocket launch is a failure. Shortly after launch, it breaks apart and falls into the sea.
May 24 - A spokesperson for South Korea's Defense Ministry says that based on analysis of commercial satellite images at North Korea's nuclear test site, North Korea appears ready to carry out a nuclear test at anytime.
December 12, 2012 - North Korea successfully launches an Unha-3 long-range rocket from the Sohae Space Center in Cholsan County and puts a "working satellite" into orbit, days after Pyongyang suggested the launch could be delayed.
2013 January 24, 2013 - North Korea's National Defense Commission says it will continue nuclear testing and long-range rocket launches, all of which are a part of an "upcoming all-out action" aimed at the United States, "the sworn enemy of the Korean people." Two days prior to this statement, the United Nations Security Council condemned a recent rocket launch by North Korea and expanded sanctions.
February 12, 2013 - Conducts its third underground nuclear test. This is the first nuclear test carried out under leader, Kim Jong Un.