By Josh Smith SEOUL (Reuters) – This January has been one of the busiest months ever for North Korea’s missile testing, with launches displaying a dizzying array of weapon types, launch locations, and increasing sophistication. From hypersonic missiles and long-range cruise missiles to missiles launched from railcars and airports, the tests highlight the nuclear-armed state’s rapidly expanding and advancing arsenal amid stalled denuclearisation talks. North Korea hasn’t tested its longest-range intercontinental ballistic missiles or nuclear weapons since 2017, but leader Kim Jong Un has pushed…