singapore japanese defence minister gen nakatani say saturday japan south korea agree expand emergency communication system defense ministries include add new direct line defense minister tensions high region since early january north korea conduct fourth nuclear test follow satellite launch test various missiles recently fail launch tuesday mean make use phone emergency communication security-related emergencies missile launch occur communication coordination defense authorities two countries need nakatani tell reporters shangri-la dialogue regional security forum singapore say emergency phone line would expand include new direct link two countries defense minister nakatani say talk would continue share safeguard sensitive information pyongyang missile nuclear program framework south korea would pass relevant information unite state seoul already legally-binding pact share safeguard intelligence call general security military information agreement gsomia unite state would pass information japan would work similarly way around since unite state also sign gsomia japan south koreans voice concern sign security pact japan one-time colonial ruler besides historical issue stem japan annexation korean peninsula end 1945 tie chill long-running territorial dispute group tiny islets japan south korea set direct line defense minister