North Korea conducted its 10th missile test of the year on Wednesday, launching an “unknown projectile” from an airfield near the capital Pyongyang, according to South Korea, who said the test failed.
Analysts said the missile might have been a Hwasong-17 intercontinental ballistic missile, known as the monster missile, which is feared to be capable of carrying more than one nuclear warhead, if effective.
The nuclear-armed regime of Kim Jong-un has conducted a series of tests in recent months, including hypersonic missiles that can fly at five times the speed of sound.
In the third hypersonic test this year, on January 13, Pyongyang tested a “boost glide” hypersonic vehicle, which apparently hit a target 1,000 kilometres away.
Analysts are sceptical about how effective these weapons – which are highly experimental – actually are. Some scientists claim the extreme heat from air friction caused by drag at such speeds could make the weapons highly unstable, possibly rendering targeting systems ineffective.
These problems are a challenge for China and the US, raising further doubts that Mr Kim's much smaller military has the funding or expertise to effectively use the weapons.
The tests are nonetheless widely condemned for raising tensions on the heavily militarised Korean Peninsula.
The US has accused North Korea of “seeking attention” with the testing, in the words of US Secretary of State Antony Blinken. Few believe tests are a lead-up to a new war with South Korea. The last ended in 1953, leaving decades of simmering tensions and fears that a new conflict could kill millions.
Tests continued during lulls in tension, such as the summits between Mr Kim and Donald Trump and after Joe Biden's inauguration, and low points – including a threat by Mr Trump to destroy North Korea in a “sea of fire”, and North Korean threats to fire a nuclear weapon at the US.
Below is a timeline of recent tests and tensions, excluding earlier leaps in North Korea's missile development in the 1990s.
2017
July 4-28 North Korea test fires the Hwasong-14 intercontinental ballistic missile (ICBM), with a claimed operational range of up to 10,000km.
August 8 US President Donald Trump warns North Korea that it might face “fire and fury”.
August 29 North Korea fires Hwasong-12 intermediate range ballistic missile (IRBM) with a claimed operational range of nearly 800km.
September 3 North Korea carries out its sixth nuclear test, saying it has mastered hydrogen bomb technology.
September 14 North Korea fires a Hwasong-12 IRBM.
September 23 US B-1B bomber flies over the Korean Demilitarised Zone.
November 29 North Korea test fires Hwasong-15 ICBM, capable of reaching the entire United States, and declares it has become a nuclear power.
2018
April 27 North Korea’s Mr Kim and South Korean President Moon Jae-in meet for first inter-Korean summit in more than a decade, pledging to work for “complete denuclearisation of the Korean Peninsula”. They meet again in May and September.
June 12 Mr Kim and Donald Trump hold their first summit, in Singapore, agreeing to denuclearisation of the Korean Peninsula in exchange for US security guarantees.
September 9 North Korea displays ICBMs at military parade.
2019
February 28 Mr Trump and Mr Kim end their second summit in the Vietnamese capital of Hanoi without an agreement owing to differences over demands by Pyongyang for sanctions relief.
May 4 Mr Kim supervises tests of rockets and a new short-range ballistic missile (SRBM) in first such tests since the November 2017 ICBM launch.
May 9 North Korea fires two KN-23 SRBMs, or submarine-launched ballistic missiles, something analysts call a significant step in capability.
May 10 Mr Trump said he did not consider the North’s missile tests a “breach of trust,” calling it “standard stuff”.
July 23 Mr Kim inspects a large, new submarine, possibly designed for SLBMs.
July 25 North Korea launches KN-23 SRBMs.
August 2 North Korea fires two more KN-23 SRBMs; Mr Trump says the tests do not breach his agreement with Mr Kim.
August 6, 10, 16 North Korea fires more KN-23 and tactical missiles.
August 24 Mr Kim oversees the test of a new “super-large” multiple launch rocket system (MLRS).
September 10 North Korea tests “super-large” MLRS.
October 2 North Korea test-fires new Pukguksong-3 SLBMs.
October 31 North Korea tests the “super-large” MLRS.
2020
January 1 Mr Kim vows to further develop nuclear programmes and introduce a “new strategic weapon”.
March 3, 9, 14 North Korea tests MLRS and short-range missiles.
March 21 Mr Kim supervises test of new tactical guided weapon; Mr Trump sends letter to Kim offering help on the new coronavirus.
March 29 North Korea tests “super-large” MLRS.
October 3 Mr Kim sends a get-well message to Mr Trump who tested positive for Covid-19.
October 10 North Korea unveils a new ICBM and SLBM at a military parade.
October 22 Mr Trump says he has a very good relationship with Mr Kim and stopped war; Joe Biden likens Mr Kim to Nazi Germany’s Adolf Hitler and calls him a “thug”.
2021
March 21 North Korea conducts two cruise missile tests, the first during Mr Biden’s presidency.
August 27 The IAEA says North Korea is again producing plutonium that could be used in nuclear weapons.
September 13 North Korea announces successful cruise missile tests.
2022
January North Korea conducts a flurry of tests, launching what analysts call “boost glide” hypersonic vehicles. Japan condemns the tests as "extremely regrettable".
February 27 North Korea launches ballistic missile over Sea of Japan, claiming test is for launching reconnaissance satellite.
March 16 North Korea test launches "unknown projectile" from military airfield.
