- Beginnings -

North Korea's nuclear ambitions date back to 1953, when hostilities in the Korean War ended in a stalemate.

In the 1960s, Pyongyang receives nuclear technology and hardware from the Soviet Union -- a key Cold War ally -- to create a nuclear energy programme.

Scientists are believed to be working on a clandestine nuclear weapons programme by the 1980s, having reverse-engineered missiles from a Soviet-era Scud.

- Longer range -

Pyongyang carries out its first test of Scud-style Hwasong missiles in 1984.

It begins developing longer-range missiles from 1987, including the Taepodong-1 (2,500 kilometres or 1,550 miles) and Taepodong-2 (6,700 km).

The programme receives a major boost, possibly including warhead design blueprints, from rogue Pakistani nuclear scientist Abdul Qadeer Khan in the 1990s.

The Taepodong-1 is test-fired over Japan in 1998, but Pyongyang declares a moratorium on such tests the next year as ties with the United States improve.

- 2006-13: Nuclear tests -

North Korea ends the moratorium in 2005, blaming "hostile" US policy under President George W. Bush, and carries out its first nuclear test on October 9, 2006.

A second underground nuclear test is carried out in May 2009, several times more powerful than the first.

Kim Jong Un succeeds as leader of North Korea after the death of his father Kim Jong Il in December 2011, and oversees a third nuclear test in 2013.

- 2016: Japanese waters -

Pyongyang claims a fourth underground nuclear test in January 2016 is a hydrogen bomb.

In August, it launches a ballistic missile directly into Japanese-controlled waters for the first time. It then successfully tests another submarine-launched ballistic missile (SLBM) the same month.

A fifth nuclear test follows in September.

- 2017: 'Fire and fury' -

Pyongyang launches multiple ballistic missiles between February and May that land in the Sea of Japan, also known as the East Sea. It says the tests are drills for possible attacks on US bases in Japan.

It says in May it has tested an intermediate-range ballistic rocket, the Hwasong-12, which flies 700 km.

On July 4, North Korea announces it successfully tested an intercontinental ballistic missile (ICBM) capable of reaching Alaska -- a gift for the "American bastards" announced on US Independence Day.

A second ICBM test follows the same month.

Then-president Donald Trump threatens Pyongyang with "fire and fury" over its missile programme.

- 2017: Largest nuclear test yet -

North Korea conducts its sixth and largest nuclear test on September 3, 2017. Monitoring groups estimate a yield of 250 kilotons, 16 times the size of the US bomb that destroyed Hiroshima in 1945.

Trump declares North Korea a state sponsor of terrorism and imposes fresh sanctions.

Pyongyang launches a new Hwasong-15 ICBM on November 29, which it claims could deliver a "super-large heavy warhead" anywhere on the US mainland.

Analysts doubt that Pyongyang has mastered the advanced technology needed for the rocket to survive re-entry into the Earth's atmosphere.

- 2018: Detente -

Pyongyang says on April 21, 2018, that nuclear tests and ICBM launches will cease immediately and that its nuclear test site will be dismantled ahead of a first meeting between Trump and Kim in Singapore in June.

- 2019-2021: New weapons, new tensions -

A second summit between Trump and Kim in Hanoi collapses in February 2019.

Tensions mount again in 2021, with North Korea carrying out a number of weapons tests, including a claimed SLBM launch, another launched from a train, and what it says is a hypersonic glide missile.

- March 2022: 'Monster' missile -

On March 16, Pyongyang fires a suspected Hwasong-17, which analysts have dubbed the "monster missile". But it explodes immediately after launch.

Days later, Pyongyang successfully fires an ICBM on March 24 -- which it claims is the Hwasong-17.

But Washington and Seoul suspect it was actually an older Hwasong-15, and that Pyongyang faked a "monster missile" launch for domestic propaganda reasons.

- September-October 2022: Tactical nuclear drills -

After Kim announces earlier in the year that he will accelerate nuclear development, North Korea changes its laws in September to allow a preventive nuclear strike and declares itself an "irreversible" nuclear power.

On October 4, Pyongyang fires an intermediate-range ballistic missile (IRBM) over Japan for the first time in five years, prompting Tokyo to issue a rare warning for people to take shelter.

North Korea says a week later the test launch of a new IRBM was part of two-week-long "tactical nuclear" drills overseen by Kim.

- November 2022: Record-breaking blitz -

Pyongyang fires more than 20 missiles on November 2 -- including one that lands close to South Korean waters -- and an artillery barrage into a maritime "buffer zone", part of what it says is a response to large-scale US-South Korea air drills.

One short-range ballistic missile crosses the de facto maritime border, with residents on Ulleungdo island told to seek shelter. South Korean President Yoon Suk-yeol slams it as "effectively a territorial invasion".

North Korea fires three more missiles the next day, including an ICBM that Seoul says failed.

Then on November 18, Pyongyang fires another ICBM, which Tokyo says might be able to hit the US mainland, depending on the weight of its warhead.

The ICBM launch comes a day after Pyongyang warned of "fiercer" military action if the US strengthened its "extended deterrence" commitment to South Korea and Japan against the North's military actions.

burs/cha/aha