By Jack Kim SEOUL (Reuters) – North Korea said on Tuesday it had tested the isolated state’s newest ICBM on Monday to gauge the war readiness of its nuclear force against mounting U.S. hostility, as Washington and its allies began operating a real-time missile data sharing system. North Korean state media said leader Kim Jong Un watched Monday’s launch of the Hwasong-18 intercontinental ballistic missile (ICBM) at a site east of the capital, Pyongyang. The missile reached an altitude of 6,518 km (4,050 miles), flying 1,002 km and accurately hitting the intended target, an empty patch of sea, s…