Timeline: Key recent weapons tests by North Korea

North Korea launched an intermediate-range missile that flew over Japan in its longest-ever flight, showing that leader Kim Jong Un is defiantly pushing to bolster his weapons programs despite U.S.-led international pressure. A look at the recent weapons tests:

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May 14: North Korea fires a newly developed intermediate-range Hwasong-12 missile it says can carry a heavy nuclear warhead.

May 21: North Korea tests a Pukguksong-2 missile that uses solid fuel, which is harder to detect by outsiders before launch.

June 8: North Korea fires several projectiles believed to be short-range surface-to-ship cruise missiles.

July 4: North Korea test-launches its first intercontinental ballistic missile, the Hwasong-14, at a highly lofted trajectory.

July 28: North Korea fires another Hwasong-14, again at a lofted trajectory, but outsider experts say its full range would reach far into the U.S mainland, including cities such as Chicago.

Aug. 9: North Korea announces a detailed plan to launch a salvo of ballistic missiles toward the U.S. Pacific territory of Guam, a major military hub and home to U.S. bombers.

Aug. 29: North Korea fires an intermediate-range Hwasong-12 that flies over Japan before plunging into the northern Pacific Ocean.

Sept. 3: North Korea carries out its sixth and most powerful nuclear test to date, claiming it was a hydrogen bomb.

Sept. 15: North Korea fires an intermediate-range missile over Japan into the Pacific; it flew about 3,700 kilometres (2,300 miles), its longest-ever flight.