Some 300 Japanese and US military personnel today carried out live-fire artillery training in northern Japan, amid high regional tensions over North Korean missile threats. <br/><br/>Officials said the drill, part of a 19-day exercise, came after a tense war of words between the United States and North Korea over Pyongyang's threats to fire missiles towards the Pacific island of Guam. <br/><br/>Troops from Japan's Ground Self-Defence Force (GSDF) and US Marines fired live ammunition from armed vehicles at a manoeuvre area on the northern island of Hokkaido.<br/><br/>The two forces began the Northern Viper 2017 exercise on August 10, involving a total of 1,300 GSDF troops and 2,000 Marines.