Angered by U.N. Security Council sanctions over its nuclear test, North Korea threatens for the first time to launch a preemptive nuclear strike against the U.S. and South Korea.
It's one of a series of provocative threats and, in some cases, actions by North Korea that begin with Pyongyang saying it is scrapping the 1953 truce that effectively ended the Korean War. At the same time, it cuts off its direct phone links with South Korea at Panmunjom, the abandoned village that sits on the border between the two countries.
North Korea then doubles down on the threat, saying it is nullifying the joint declaration on the de-nuclearization of the Korean Peninsula. One of the country's top generals, according to published reports, claims Pyongyang has nuclear-tipped intercontinental ballistic missiles that are ready to be fired.
Although U.S. officials don't believe North Korea is in a position to strike the United States, the Obama administration responds to the threat by announcing plans to deploy additional ground-based missile interceptors on the West Coast.
U.S. officials also say B-52 bombers are making flights over South Korea as part of annual, joint military exercises this month that have enraged North Korea.
Pyongyang releases a new propaganda video that shows an imagined missile attack on U.S. government buildings in Washington, including the White House and the Capitol. The roughly four-minute video is posted on the YouTube channel of the North Korean government website, Uriminzokkiri.
North Korea threatens to attack U.S. and South Korea bases, putting its troops on alert. It announces through state-run media that the military is ready for combat. The threat follows claims that U.S. B-52 bombers again made flights over South Korea. Later it's revealed that F-22 Raptors and B-2 stealth bombers also take part in the U.S.-South Korea drills.
Pyongyang says it's readying rockets aimed at U.S. targets, releasing photos that show Kim meeting with military officials with strike plans on U.S. maps visible in the background. The North also cuts its last military hotline with South Korea.
North Korea begins the month pledging to restart its Yongbyon nuclear complex, including a uranium enrichment plant and a reactor that was shut down under an agreement reached in October 2007 during talks among North Korea, the United States and four other nations. U.S. Secretary of State John Kerry responds by warning the United States will not accept North Korea as a "nuclear state."
Later that week, Pyongyang warns that it cannot guarantee the safety of safety of embassies and international organizations in the event of armed conflict. It comes as a U.S. official tells CNN that two medium-range missiles have been loaded onto mobile launchers along North Korea's east coast.
Tensions then move to a joint industrial complex that serves as an important symbol of cooperation between the two countries. The Kaesong Industrial Complex sits on the North's side of the border but houses operations of scores of South Korean companies. Pyongyang blocks the entrance of hundreds of South Korean workers to Kaesong, where more than 50,000 North Koreans work, producing hundreds of millions of dollars worth of goods each year.
Soon after, North Korea warns foreigners to secure shelter or evacuate in case of hostilities, as Japan moves its missile defense systems into place at three sites around Tokyo.
A U.S. official, who declined to be named because of the sensitivity of the information, tells CNN recent intelligence suggests that a missile test could be "imminent."
Meanwhile, North Korea's state media published articles that described festive events, suggesting a much less fraught situation inside the country.
The state-run Korean Central News Agency (KCNA) reported that various sporting events were happening or scheduled to take place to mark the 101st anniversary of the birth of Kim Il Sung, the founder of North Korea and the grandfather of Kim Jong Un.
"The ongoing sports tournaments make the country seethe with holiday atmosphere," KCNA said. Kim Il Sung's birthday, known as the Day of the Sun, is a major public holiday in North Korea.