From Wikipedia:
12 October 1994: the United States and North Korea signed the "Agreed Framework": North Korea agreed to freeze its plutonium production program in exchange for fuel oil, economic cooperation, and the construction of two modern light-water nuclear power plants. Eventually, North Korea's existing nuclear facilities were to be dismantled, and the spent reactor fuel taken out of the country.
18 March 1996: Hans Blix tells the IAEA's Board of Governors North Korea has still not made its initial declaration of the amount of plutonium they possess, as required under the Agreed Framework, and warned that without the declaration IAEA would lose the ability to verify North Korea was not using its plutonium to develop weapons.
3–5 October 2002: On a visit to the North Korean capital Pyongyang, US Assistant Secretary of State James Kelly presses the North on suspicions that it is continuing to pursue a nuclear energy and missiles programme.
16 October 2002: The US announces that North Korea admitted in their talks to a secret nuclear arms programme.
4 December 2002: The North rejects a call to open its nuclear facilities to inspection.
12 December 2002: The North pledges to reactivate nuclear facilities for energy generation, saying the Americans' decision to halt oil shipments leaves it with no choice. It claims the US wrecked the 1994 pact.
13 December 2002: North Korea asks the UN's International Atomic Energy Agency (IAEA) to remove seals and surveillance equipment - the IAEA's "eyes and ears" on the North's nuclear status—from its Yongbyon power plant.
27 December 2002: North Korea says it is expelling the two IAEA nuclear inspectors from the country. It also says it is planning to reopen a reprocessing plant, which could start producing weapons grade plutonium within months.
6 January 2003: The IAEA passes a resolution demanding that North Korea readmit UN inspectors and abandon its secret nuclear weapons programme "within weeks", or face possible action by the UN Security Council.
31 January 2003: White House spokesman Ari Fleischer delivers a stern warning that North Korea must not take "yet another provocative action... intended to intimidate and blackmail the international community"
9 April 2003: The United Nations Security Council expresses concern about North Korea's nuclear programme, but fails to condemn Pyongyang for pulling out of the Nuclear Non-proliferation Treaty.
3 October 2006: North Korea announces plans to test a nuclear weapon in the future, blaming "hostile US policy".[27] Their full text can be read at BBC News.
5 October 2006: A US envoy directly threatens North Korea as to the upcoming test, stating "It (North Korea) can have a future or it can have these (nuclear) weapons, it cannot have them both." The envoy also mentions that any attempt to test a nuclear device would be seen as a "highly provocative act".
6 October 2006: The United Nations Security Council issues a statement declaring, "The Security Council urges the DPRK not to undertake such a test and to refrain from any action that might aggravate tension, to work on the resolution of non-proliferation concerns and to facilitate a peaceful and comprehensive solution through political and diplomatic efforts. Later in the day, there are unconfirmed reports of the North Korean government successfully testing a nuclear bomb."
9 October 2006: North Korea announces that it has performed its first-ever nuclear weapon test.
Which makes this Obama quote from NPR even more of a joke:
And then in years 13 and 14, it is possible that those breakout times would have been much shorter, but at that point we have much better ideas about what it is that their program involves. We have much more insight into their capabilities. And the option of a future president to take action if in fact they try to obtain a nuclear weapon is undiminished.