North Korea's announcement on Saturday that it had entered a "state of war" with South Korea was the latest in a long line of escalating threats and postures adopted by all sides in the current crisis on the Korean peninsula.
Below is a timeline of key threats and actions dating from the North's long-range rocket launch in December 2012.
Dec 12: North Korea successfully launches three-stage rocket and places satellite in orbit. Seoul, Washington and UN condemn launch as a covert ballistic missile test.
Jan 22: UN Security Council passes a resolution condemning North Korea's rocket launch and tightens existing sanctions.
Jan 24: North Korea's National Defense Commission says it will proceed with a "high-level nuclear test."
Jan 25: North Korea threatens "physical counter-measures" against rival South Korea.
Feb 12: North Korea conducts a third nuclear test.
Feb 26: North Korean leader Kim Jong-Un oversees a live-fire artillery drill aimed at simulating an "actual war".
March 1: South Korea and US launch annual "Foal Eagle" joint military exercise.
March 5: North Korea says it will scrap armistice that ended the 1950-53 Korean War.
March 7: North Korea threatens a "pre-emptive" nuclear strike against the United States and South Korea.
March 7: The United Nations adopts tougher sanctions on Pyongyang over its nuclear test.
March 8: North Korea announces the voiding of non-aggression pacts with South Korea and severs a government hotline with Seoul. Kim Jong-Un tours frontline island units and vows "all-out war".
March 11: South Korea and US launch annual "Key Resolve" joint military exercise.
March 12: Kim Jong-Un threatens to "wipe out" South Korean island of Baengnyeong.
March 15: Defense secretary Chuck Hagel announces plans to bolster US mainland defenses against a possible North Korean missile strike.
March 18: US Deputy Defense Secretary Ashton Carter promises to provide South Korea with every military resource under the US nuclear umbrella.
March 19: US publicises flights by nuclear-capable B-52 bombers over South Korea as part of "Foal Eagle" exercise.
March 21: North Korean army threatens strikes against US military bases in Japan and Guam in response to B-52 flights.
March 22: South Korea and US sign new pact providing for a joint military response even to low-level provocation by North Korea.
March 26: South Korean President Park Geun-Hye warns North Korea its only "path to survival" lies in abandoning nuclear and missile programmes.
March 26 : North Korea's military puts its "strategic" rocket units on a war footing, with fresh threat to strike targets on the US mainland, Hawaii and Guam and South Korea.
March 27: North Korea cuts last remaining military hotline with South Korea.
March 28: The United States deploys two nuclear-capable B-2 stealth bombers on "deterrence" missions over South Korea. Hagel says US ready for "any eventuality."
March 29: Kim Jong-Un, vowing to "settle accounts," orders missile units to prepare to strike US mainland and military bases in the Pacific.
March 30: North Korea declares it had entered into a "state of war" with South Korea.