SEOUL, South Korea (AP) — North Korea has conducted its fifth nuclear test on Friday, just eight months after it claimed it successfully detonated a small hydrogen bomb. Analysts say that the North's newest test, which South Korea says produced its biggest-ever explosive yield, shows Pyongyang's stubborn determination in face of sanctions to create smaller and lighter nuclear weapons that could be fit on future missiles capable of striking the U.S. mainland.
Some of the notable developments in North Korea's nuclear weapons and missile programs in 2016:
— Jan. 6: North Korea conducts its fourth nuclear test and says it successfully tested a "miniaturized" hydrogen bomb. Outsiders are skeptical about the H-bomb claim.
—Feb. 2: North Korea informs international organizations that it will attempt a satellite launch between Feb. 8 and 25. It later moves launch window to Feb. 7-14.
— Feb. 7: North Korea launches a long-range rocket.
—March 9: North Korean state media publicizes photos of a purported mock-up of a key nuclear warhead part. North Korean leader Kim Jong Un says the country has developed miniaturized atomic bombs that can be placed on missiles.
— March 18: North Korea for the first time since 2014 fires a medium-range Rodong missile, which flies about 800 kilometers (500 miles) before crashing into its eastern waters.
— April 23: North Korea fires a ballistic missile from a submarine. South Korean defense officials say it traveled about 30 kilometers (19 miles). North Korea says the launch was aimed at advancing nuclear warhead technologies.
— June 22: The U.S. and South Korea say North Korea fires two suspected "Musudan" missiles, which could one day be capable of reaching far-off U.S. military bases in Asia. North Korea later claims a successful test of a powerful new midrange missile, which it says reached a maximum height of 1,400 kilometers (870 miles) before landing 400 kilometers (248 miles) away in targeted waters.
— July 19: North Korea fires three ballistic missiles, with two of them flying between 500 to 600 kilometers (310 to 375 miles). North Korea says the test-firings are part of a simulated pre-emptive attack on ports and airfields in South Korea.
— Aug. 3: South Korean and Japanese officials say North Korea fired a medium-range ballistic missile, likely a Rodong, that flew about 1,000 kilometers (620) miles and landed near Japan's territorial waters.
— Aug. 24: North Korea fires a ballistic missile from a submarine that flew 500 kilometers (310 miles) before crashing into waters near Japan. Leader Kim says the country has acquired a fully-equipped nuclear attack capability and also put the U.S. mainland within striking distance.
— Sept. 5: North Korea fires three suspected medium-range missiles that travel about 1,000 kilometers (620 miles) before landing in waters near Japan.
— Sept. 9: North Korea says it has successfully conducted a nuclear warhead explosion test.