Timeline: 30 years of North Korea’s nuclear gains

1986

North Korea starts operation of a five-megawatt nuclear reactor at Yongbyon after seven years of construction with Soviet help.

1993

North Korea says it will quit the nuclear nonproliferation treaty, but later suspends its withdrawal.

1994

North Korea and the US sign an agreement under which Pyongyang shuts down the plutonium-based Yongbyon nuclear reactor in exchange for help building two nuclear reactors for producing electricity.

2002

January 29th: The US president, George W Bush, labels North Korea, Iran and Iraq an "axis of evil".

October 4th: Washington says North Korea admitted to a visiting US delegation that it has a uranium enrichment programme.

November 21st: US-led consortium says it is suspending construction of the two new reactors.

2003

January 11th: North Korea withdraws from the nuclear nonproliferation treaty.

August 27-29th: North Korea joins first round of six-nation nuclear talks in Beijing, which include China, Japan, Russia, South Korea and the US.

2005

February 10th: North Korea announces it has nuclear weapons.

2006

October 9th: North Korea conducts an underground nuclear test blast.

2011

December 19th: North Korean state media say Kim Jong-Il died two days previously of a heart attack at the age of 69, and urge people to support his son and successor, Kim Jong-un.

February 18th: Satellite images show the North has completed a launch tower at its new west coast missile base at Tongchang-ri, experts say.

2012

April 13th: Rocket is launched from Tongchang-ri and appears to have disintegrated soon after blastoff and fallen into the ocean, South Korean authorities say.

December 12th: North Korea launches long-range rocket, which the international community condemns as a disguised ballistic missile test.

2013

February 12th: North Korea conducts third and largest nuclear test so far, attracting added UN sanctions and sending military tensions on the Korean peninsula surging for months.

December 13th: North Korea announces the execution of Kim Jong-un's uncle and political mentor, in a move seen by some as a sign of internal dissent.

2015

May: North Korea says it successfully test-fired a submarine-launched ballistic missile, but experts say the exercise fell far short of a full flight test.

December 3rd: Satellite images indicate North Korea is excavating a new tunnel at its main nuclear test site at Punggye-ri, a US think tank says.

December 11th: State media cite Kim Jong-un as saying North Korea has developed a hydrogen bomb, but Washington says it doubts Pyongyang has a thermonuclear device.

2016

January 6th: North Korea says it has detonated a hydrogen bomb.

September 9th: Fifth nuclear test detected in the north east of the country.

Guardian service