North Korea has fired a new ballistic missile, South Korean military officials said, in the first such launch since mid-September.
Here are the key steps in the development of the regime's banned weapons and nuclear programme.
The beginnings, 1970s?
North Korea starts working in the late 1970s on a version of the Soviet Scud-B with a range of around 300 kilometres (around 200 miles), carrying out a first test in 1984.
Between 1987 and 1992 it begins developing longer range missiles, including the Taepodong-1 (2,500 km) and Taepodong-2 (6,700 km).
The Taepodong-1 is test-fired over Japan in 1998 but the following year Pyongyang declares a moratorium on such tests as ties with the United States improve.
First nuclear test in 2006 ?
It ends the moratorium in 2005, blaming the Bush administration's "hostile" policy, and carries out its first nuclear test on October 9, 2006.
In May 2009, there is a second underground nuclear test, several times more powerful than the first. Kim Jong-Un succeeds his father Kim Jong-Il, who dies in December 2011, and oversees a third nuclear test in 2013.
2016, Japanese waters reached?
There is a fourth underground nuclear test in January 2016, which Pyongyang claims is a hydrogen bomb.
In March, Kim Jong-Un claims the North has successfully miniaturised a thermo-nuclear warhead and in April it test-fires a submarine-launched ballistic missile.
On August 3, it fires, for the first time, a ballistic missile directly into Japanese-controlled waters; later that month it successfully test-fires another submarine-launched ballistic missile.
There is a fifth nuclear test on September 9.
2017, Japan and Guam under threat ?
Between February and May, the North tests a series of ballistic missiles that fall into the Sea of Japan or that it claims are exercises to hit US bases in Japan.
A test on May 14 is of a "newly developed mid/long-range strategic ballistic rocket, Hwasong-12", Pyongyang says. It flies 700 kilometres before landing in the Sea of Japan.
Ahead of the first meeting between South Korean President Moon Jae-In and US President Donald Trump, the North tests a rocket engine that could be fitted to an intercontinental ballistic missile (ICBM).
The following month it says it has successfully tested an ICBM capable of reaching Alaska, a gift for the "American bastards". There is a second successful ICBM test on July 28.
Hours after Trump threatens Pyongyang with "fire and fury" over its missile programme, the North says it is considering strikes near US strategic military installations in Guam.
On August 29, it fires a ballistic missile over Japan that Tokyo says is an "unprecedented, serious and grave threat".
Largest nuclear test yet ?
On September 3, North Korea conducts its sixth and largest nuclear test. Monitoring groups estimate a yield of 250 kilotons, which is 16 times the size of the 15-kiloton US bomb that destroyed Hiroshima in 1945.
On September 15, less than a week after the UN adopts an eighth series of sanctions, North Korea fires a intermediate-range missile over Japan, at a distance of 3,700 kilometres (2,299 miles), according to Seoul.
On November 20 Washington declares North Korea a state sponsor of terrorism, a day before it heaps pressure on the hermit state by slapping it with fresh sanctions.
On November 28 North Korea fires a new ballistic missile, which flies east from South Pyongan Province, the South Korean military Joint Chiefs of Staff (JCS) says.