The Associated Press
Recent events in the escalation of nuclear tensions on the Korean Peninsula:
-- March 7: The U.N. Security Council imposes tough sanctions against North Korea to punish it for conducting a nuclear test on Feb. 12 in defiance of U.N. resolutions banning it from nuclear and missile activity. North Korea characterized the test, its third since 2006, as a defensive act against U.S. aggression.
-- March 11: South Korea and the U.S. begin annual joint military drills. North Korea, which calls the maneuvers preparation for an invasion, responds by following through on a threat to cut a hotline with South Korea and void the 60-year-old armistice ending the Korean War.
-- March 12: North Korean state media report that the country's leader, Kim Jong Un, urged front-line troops to be on "maximum alert" and warned that "war can break out right now."
-- March 20: Coordinated cyberattacks in South Korea knock out computers and servers at three major TV networks and three banks. The source of the attacks remains under investigation but North Korean involvement is suspected. A week later, organizations of North Korean defectors say their computer systems also were attacked.
-- March 22: North Korea condemns a U.N. resolution approving a formal investigation into its suspected human rights violations and says it will ignore the measure.
-- March 27: North Korea cuts a military hotline to its Kaesong industrial complex, which is jointly run with the South and is the last major example of inter-Korean cooperation. Operations at the complex continue.
-- March 28: In a show of force, the U.S. takes the unprecedented step of announcing that two of its nuclear-capable B-2 bombers joined the military drills with South Korea and dropped dummy munitions on an island range. It had earlier announced the participation of older nuclear-capable B-52 bombers.
-- March 29: Kim convenes an "urgent operation meeting" of senior generals just after midnight, signs a rocket preparation plan and orders his forces on standby to strike the U.S. mainland, South Korea, Guam and Hawaii. State media quote him as saying that "the time has come to settle accounts with the U.S. imperialists."
-- March 30: North Korea warns that "inter-Korean relations have naturally entered the state of war," and says it would retaliate against any U.S. and South Korean provocations without notice. It says hostilities "will not be limited to a local war, but develop into an all-out war, a nuclear war."
-- March 31: The Central Committee of North Korea's ruling Workers' Party says the country's nuclear weapons are "the nation's life" and will not be traded even for "billions of dollars."
-- April 1: The U.S. announces it sent F-22 stealth fighter jets to participate in the U.S.-South Korean war games.
-- April 2: North Korea's atomic energy department says it will restart a plutonium reactor and a uranium enrichment plant at its main Nyongbyon nuclear complex and increase production of nuclear weapons material. The U.S. says it would be "extremely alarming" if the North follows through.
-- April 3: North Korea bars South Koreans from going to their jobs at the Kaesong industrial complex and closes the border to trucks carrying raw materials for the factories.
Copyright 2013 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.