 Meanwhile , the United Nations Security Council voted to send assistance to the collapsing country and United States President Harry S. Truman subsequently ordered ground troops into the nation . However , U.S. forces in the Far East had been steadily decreasing since the end of World War II , five years earlier . At the time , the closest force was the 24th Infantry Division of the Eighth United States Army , stationed in Japan under the command of William F. Dean . Tellingly , the division was under strength and most of its equipment was antiquated due to reductions in military spending . Yet in spite of these deficiencies the division was ordered into South Korea , tasked with taking the initial " shock " of the North Korean advances until the rest of the Eighth Army could arrive and establish a defense . 
