(CNN)Here's some background information about the Democratic People's Republic of Korea (DPRK), also called North Korea. It borders China, Russia and South Korea.
About North Korea:
(from the CIA World Factbook)
Area: 120,538 sq km, slightly smaller than Mississippi
Population: 24,851,627 (July 2014 est.)
Median age: 33.4 (2014 est.)
Ethnic Groups: Racially homogenous, small ethnic Chinese and Japanese populations
Religion: Traditionally Buddhist and Confucianist, with some Christian and other sects
GDP: $40 billion (July 2012 estimate)
GDP per capita:$1,800 (2011 estimate)
North Korea has no diplomatic representation in the United States. They do have a permanent mission to the United Nations.
The U.S. does not have any diplomatic representation in North Korea. The Swedish Embassy represents the U.S. as consular protecting power.
August 1945 - After Japan surrenders in World War II, the U.S. occupies the southern half of the peninsula while the U.S.S.R occupies the northern half.
1945-1994 - Kim Il-Sung is the country's first leader.
1948 - Separate governments for the northern and southern parts of the Korean peninsula are established after an international stalemate fails to resolve the issue.
2000 - Kim Dae Jung, the leader of South Korea and Kim Jong Il meet for the first time since the country was separated 50 years earlier.
January 10, 2003 - North Korea withdraws from the Nuclear Non-Proliferation Treaty.
April 23, 2003 - North Korea declares it has nuclear weapons.
December 11, 2007 - Freight trains begin crossing the border between North and South Korea, resuming a regular service that last ran in the 1950s.
March 3, 2008 - After the U.S. and South Korea begin six days of joint military exercises, North Korea's foreign minister denounces the exercises and warns that North Korea will explore all countermeasures necessary for its protection. Approximately 27,000 U.S. troops and aircraft carrier USS Nimitz take part in the exercises.
December 28, 2008 - The freight trains that began crossing between the border of North and South Korea in December 2007 suspend service due to souring relations between the two countries, dashing hopes of reconciliation.
March 8, 2009 - The Supreme People's Assembly holds elections, delayed since August 2008. Kim Jong Il is unanimously re-elected in his district, with a 100% voter turnout.
August 4, 2009 - Former President Bill Clinton sits down with Kim Jong Il to discuss the release of American journalists Euna Lee and Laura Ling. Both Lee and Ling are later given a full pardon from Kim Jong Il and released.
May 20, 2010 - South Korea formally accuses North Korea of firing a torpedo to sink the Cheonan, a South Korean Navy ship, in March, killing 46 sailors. North Korea denies responsibility and warns that any retaliation would lead to "all-out war."
May 24, 2010 - South Korean President Lee Myung-bak severs all trade ties and asks the U.N. Security Council to punish North Korea.
September 28-29, 2010 - North Korea's ruling party, the Workers' Party of Korea, meets for the first time since 1980. Kim Jong Il is re-elected as general secretary of the party.
November 23, 2010 - North Korea launches artillery at Yeonpyeong Island in South Korea, killing two South Korean marines.
February 7-9, 2011 - Military officials from both North and South Korea meet at the DMZ to defuse tensions and restart international aid talks without much success.
April 29, 2011 - The U.S. State Department refutes charges by former President Jimmy Carter that the U.S. and South Korea are withholding food aid from North Korea for political motives. The U.S. had suspended aid two years ago to North Korea because it suspected the donated food was not reaching those most in need.
April 29, 2011 - The United Nations World Food Programme announces plans to begin emergency food distribution to 3.5 million North Koreans, primarily women and children, who are starving after a harsh winter destroyed crops.
December 17, 2011 - North Korean leader Kim Jong Il dies at the age of 69.
December 31, 2011 - His son, Kim Jong Un assumes command of the North Korean army.
April 13, 2012 - North Korea's long-range rocket launch is a failure. Shortly after launch, it breaks apart and falls into the sea.
July 16, 2012 - Ri Yong Ho, the North Korea army chief, is relieved of all government posts, allegedly due to illness.
December 12, 2012 - North Korea successfully launches an Unha-3 long-range rocket from the Sohae Space Center in Cholsan County and puts a "working satellite" into orbit, days after Pyongyang suggested the launch could be delayed.
January 22, 2012 - The United Nations condemns the recent North Korean rocket launch and expands existing sanctions against North Korea with Resolution 2087.
January 24, 2013 - North Korea's National Defense Commission says it will continue nuclear testing and long-range rocket launches, all of which are a part of an "upcoming all-out action" aimed at the United States, "the sworn enemy of the Korean people."
March 5, 2013 - North Korea threatens to nullify the armistice agreement that ended the Korean War in 1953, citing U.S.-led international moves to impose new sanctions against it over its recent nuclear test.
March 11, 2013 - A spokesman for the North Korean military announces that the 1953 armistice is being "scrapped."
March 27, 2013 - North Korea cuts its military hotline with South Korea. Earlier in the month a Red Cross hotline through Panmunjom is cut.
May 18, 2013 - Launches short-range guided missiles off the Korean Peninsula away from South Korea's waters.
December 13, 2013 - Kim Jong Un's uncle, Jang Song Thaek, is executed. Jang had once been considered the second-most powerful person in the country. North Korea's official news agency accuses Jang of trying to overthrow the state, describing him as "despicable human scum."
February 17, 2014 - The United Nations Commission of Inquiry on Human Rights publishes a report on widespread human rights abuses in North Korea.
December 19, 2014 - The FBI says it has concluded the North Korean government is responsible for a cyberattack on Sony Pictures. In November, hackers broke into Sony's servers, published private emails and information and threatened to attack movie theaters screening "The Interview," a comedy film about an assassination plot on North Korean leader Kim Jong Un.
March 2, 2015 - Although the U.N. bans North Korea from testing missiles, North Korea launches two Scud-type ballistic missiles towards the Sea between Korea and Japan.
March 11, 2015 - The Russian Foreign Ministry announces an agreement that 2015 will be a "Year of Friendship" between the two countries and that Kim Jong-Un will visit Moscow.
March 26, 2015 - North Korea claims to arrest two South Korean men for "spying" and accuses them of collecting intelligence and military secrets from North Korea.