Factbox: North Korea's missile and nuclear tests

North Korean Leader Kim Jong Un guides the Korean People's Army Tank Crews' Competition 2017 in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang on April 1, 2017. KCNA/via REUTERS

SEOUL (Reuters) - A Chinese envoy arrives in South Korea on Monday to discuss North Korea's increasingly defiant weapons programme as a U.S. Navy strike group heads to the region amid concerns Pyongyang may be readying a fresh nuclear test. The following is a timeline of North's Korea's nuclear and missile tests. Aug. 1998: North Korea fires a multistage, long-range missile called Taepodong-I over Japan into the Pacific Ocean. North Korea called it a satellite launch. July 2006: North Korea test-fires a Taepodong-2 missile, which the United States says failed after launch. Oct. 2006: North Korea conducts first nuclear test. April 2009: North Korea says it successfully launches three-stage Unha-2 rocket carrying satellite. Washington says it failed. May 2009: North Korea explodes a nuclear device underground. April 2012: A slightly modified Unha-3 rocket explodes just after take-off. The North concedes failure. Dec. 2012: North Korea again launches a Unha-3 rocket, saying it successfully put a satellite into orbit. U.S. officials confirm an object in orbit, but no signal is detected. Feb. 2013: North Korea carries out third nuclear test. Jan. 6, 2016: North Korea says it successfully tests a hydrogen bomb. April 15, 2016: North Korea attempts to launch a Musudan missile but fails. Feb. 7, 2016: North Korea launches a long-range rocket, which it says put a satellite into orbit June 22, 2016: North Korea conducts two tests of an intermediate range Musudan missile after four failed launches of the same kind. July 18, 2016: North Korea fires three ballistic missiles off its east coast with a 500 km-600 km range. Aug. 3, 2016: North Korea fires two missiles, one of them landing in Japan's economic exclusion zone. Aug. 24, 2016: North Korea launches ballistic missile from a submarine, which flies 500 km. Sept. 5, 2016: North Korea fires three ballistic missiles about 1,000 kms (620 miles), one of which enters Japan’s air defence zone Sept. 9, 2016: North Korea conducts fifth nuclear test Sept. 20, 2016: North Korea says it complete ground test of a new rocket engine, which South Korea says is likely to be used for a long-range missile. Feb. 12, 2017: North Korea fires intermediate-range Pukguksong-2 ballistic missile into nearby seas. March 6, 2017: North Korea fires four ballistic missiles, three of them falling into Japan’s exclusive economic zone. March 19, 2017: North Korea announces rocket engine test, saying it will help country achieve “world-class satellite launch capability” March 22, 2017: A North Korean missile appears to explode just after launch. April 5, 2017: North Korea fires ballistic missile into the sea off its east coast. U.S. officials say it appears to be a liquid-fueled, extended-range Scud missile. (Reporting by Ju-min Park; Editing by Bill Tarrant and Lincoln Feast)