Here is a look at recent incidents involving North Korea and international efforts to stop the communist state's nuclear and missiles programs that have led to rising tensions on the Korean peninsula.
April 5, 2009 - North Korea launches missile carrying a satellite over the Sea of Japan. The test fails to make orbit, but prompts unanimous condemnation by the U.N. Security Council as a violation of sanctions barring the use of ballistic missile technology. Nine days later, North Korea condemns the U.N. Security Council statement and withdraws from the "Six Party Talks" meant to rein in its nuclear program. It also announces its intention to reactivate its nuclear facilities.
May 25, 2009 - North Korea announces a new test of a nuclear explosive device, its first since October 2006. The next month U.N. Security Council unanimously adopts expanded sanctions on Pyongyang.
July 3-4, 2009 - North Korea fires a series of short-range ballistic missiles into the Sea of Japan. Additional missile tests take place in October.
December 8, 2009 - U.S. North Korea envoy Stephen Bosworth begins three-day visit to Pyongyang in first direct high-level contact between North Korea and the U.S. Obama administration. Talks are inconclusive.
October 24-25, 2011 - The United States and North Korea hold two days of talks in Geneva on the nuclear issue. The United States describes the tone as "positive and generally constructive."
December 17, 2011 - North Korean leader Kim Jong-il dies, an event announced two days later by the country's state-run media. He is succeeded by his son, Kim Jong-un.
February 29, 2012 - The United States and North Korea announce a "Leap Day" deal under which Pyongyang agrees to suspend major elements of its atomic program and the United States pledges to provide 240,000 tonnes of food aid.
March 16, 2012 - North Korea announces plans to launch a satellite to commemorate the centenary of the birth of its founder, Kim Il-sung. The United States and its allies condemn the plan as a test of banned ballistic missile technology that could scuttle the "Leap Day" deal. The United States suspends plans to provide food aid to the North.
April 13, 2012 - In an embarrassing setback, North Korea admits its heralded launch has failed after the rocket crashes into the sea. Days later, North Korea dismisses a rebuke by the U.N. Security Council and says it is no longer bound by an agreement with the United States for a moratorium on missile and nuclear tests and renewed arms inspections.
December 12, 2012 - North Korea launches a rocket which puts a weather satellite into orbit. It was labeled by the United States, South Korea and Japan as a test of technology that could one day deliver a nuclear warhead capable of hitting targets as far away as the United States.
Jan 23, 2013 - The UN Security Council condemns the launch and tightens existing U.N. sanctions against Pyongyang. North Korea announces it will carry out a third "high-level nuclear test".
Feb 12, 2013 - North Korea conducts its third nuclear test in defiance of U.N. resolutions, drawing condemnation from around the world, including its ally China. The U.N. Security Council month later votes to tighten financial restrictions on Pyongyang and crack down on its banned cargo trading.
March 3, 2013 - Former U.S. basketball star Dennis Rodman returns from a visit to North Korea with a message for Obama to call its young leader, Kim Jong-un. The idea is widely dismissed by U.S. officials who say they already have open lines of communication with Pyongyang.
March 7, 2013 - In response to the U.S.-led move for new U.N. sanctions, North Korea threatens the United States with a preemptive nuclear strike. It later calls the U.N. sanctions a plot to topple its leadership.
March 11, 2013 - The U.S. Treasury imposes sanctions against North Korea's Foreign Trade Bank, its main foreign exchange institution, for supporting Pyongyang's weapons of mass destruction. Japan and Australia later follow suit.
March 15, 2013 - The United States says it will bolster U.S. missile defenses in Alaska and Japan in response to threats by North Korea, which repeatedly says it would attack U.S. military bases on Japan and the Pacific Island of Guam if provoked.
March 21, 2013 - The United Nations starts an investigation into reports of widespread and systematic human rights violations in North Korea.
March 28, 2013 - During annual military exercises, the United States flies two nuclear-capable B-2 Stealth bombers on practice runs over South Korea in a rare show of force. North Korea puts its rocket units on standby to attack U.S. military bases in South Korea and the Pacific. Pyongyang also cancels its armistice agreement with the United States that ended the 1950-53 Korean War and cuts all communication lines with U.S. forces, the United Nations and South Korea.
April 2, 2013 - North Korea announces plans to revive the mothballed Yongbyon nuclear reactor able to produce bomb-grade plutonium, as a deterrent against recent U.S. threats.
April 3, 2013 - North Korea closes access to a joint factory zone with South Korea, putting at risk $2 billion a year in trade that is seen as vital for the impoverished state. The United States announces plans to send missile defenses to Guam.
April 5, 2013 - North Korea asks embassies to consider moving staff out and warns it cannot guarantee the safety of diplomats after April 10. Britain says it sees the move as part of "their continuing rhetoric that the U.S. poses a threat to them."