 In planning its new offensive , the North Korean command decided any attempt to flank the UN force was impossible thanks to the support of the UN navy . Instead , they opted to use frontal attack to breach the perimeter and collapse it as the only hope of achieving success in the battle . <unk> by intelligence from the Soviet Union the North Koreans were aware the UN forces were building up along the Pusan Perimeter and that it must conduct an offensive soon or it could not win the battle . A secondary objective was to surround <unk> and destroy the UN and ROK units in that city . As part of this mission , the North Korean units would first cut the supply lines to <unk> . 
