When the North Koreans approached the Pusan Perimeter on August 5 , they attempted the same frontal assault technique on the four main avenues of approach into the perimeter . Throughout August , the NK 6th Division , and later the NK 7th Division engaged the US 25th Infantry Division at the Battle of Masan , initially repelling a UN counteroffensive before countering with battles at Komam @-@ ni and Battle Mountain . These attacks stalled as UN forces , well equipped and with plenty of reserves , repeatedly repelled North Korean attacks . North of Masan , the NK 4th Division and the US 24th Infantry Division sparred in the Naktong Bulge area . In the First Battle of Naktong Bulge , the North Korean division was unable to hold its bridgehead across the river as large numbers of US reserve forces were brought in to repel it , and on August 19 , the NK 4th Division was forced back across the river with 50 percent casualties . In the Taegu region , five North Korean divisions were repulsed by three UN divisions in several attempts to attack the city during the Battle of Taegu . Particularly heavy fighting took place at the Battle of the Bowling Alley where the NK 13th Division was almost completely destroyed in the attack . On the east coast , three more North Korean divisions were repulsed by the South Koreans at P 'ohang @-@ dong during the Battle of P 'ohang @-@ dong . All along the front , the North Korean troops were reeling from these defeats , the first time in the war their strategies were not working .