panmunjom south korea u.s. defense secretary jim mattis emphasize diplomatic efforts resolve north korean missile nuclear crisis stand tense heavily fortify border north south friday say goal war remark come u.s. president donald trump threaten destroy north necessary leave first trip asia next week include stop south korea meet president moon jae-in part moon talk mattis say aggressive deployment u.s. strategic assets region include overflights u.s. bombers effective deter north korean threat tension north korea unite state build series nuclear missile test pyongyang bellicose verbal exchange trump north korean leader kim jong un stoke fear miscalculation could lead arm confrontation north korean provocations continue threaten regional global security despite unanimous condemnation unite nations security council mattis say prepare remark visit demilitarize zone dmz secretary state tillerson make clear goal war rather complete verifiable irreversible denuclearization korean peninsula stand alongside mattis south korean defense minister song young-moo say together continue defend peace strong strong might ahead trump visit asia mattis emphasize diplomatic efforts find peaceful solution crisis week-long trip region really keep north korea effort firmly diplomatic lane resolution mattis say early week three days meet asian defense chiefs philippines time u.s. south korean militaries look ways deter pyongyang bolster south defenses washington top military officer marine general joseph dunford chairman joint chiefs staff meet south korean counterpart general kyeong doo jeong u.s. military statement say dunford renew u.s. warn retaliation provocations dunford reaffirm attack north korea would meet response overwhelm effective use full range u.s. military capabilities statement say unite state fly air force bombers water east north korea last month show force u.s. navy say long-planned maneuver three u.s. aircraft carrier strike group pacific come days last week cia chief mike pompeo say north korea could months away develop ability hit unite state nuclear weapons scenario trump vow prevent u.s. intelligence experts say pyongyang believe need weapons ensure survival skeptical diplomatic efforts focus sanction get pyongyang denuclearize unite state thursday impose sanction seven north korean individuals three entities flagrant human right abuse include kill torture force labor hunt asylum seekers abroad speech last month unite nations trump threaten destroy north korea necessary defend unite state ally kim blast trump mentally derange despite rhetoric white house officials say trump look peaceful resolution options include military ones table military options defense attack ally attack course everyone peaceful resolution mattis tell reporters travel week one rush war separately north korea release south korean fish boat find north korean water illegally state media say crew 10 seven south koreans three vietnamese release friday even spokesman south korea coastguard tell reuters return boat report miss saturday may ease already strain relations north south two side technically still war 1950-53 conflict end truce peace treaty north regularly threaten destroy south unite state mattis talk diplomacy north korea ahead trump 's asia tour