I want to test the ability of students to read a passage and answer questions about it. Could you please come up with a good question for the passage "By August, the KPA had pushed back the ROK Army and the Eighth United States Army to the vicinity of Pusan in southeast Korea. In their southward advance, the KPA purged the Republic of Korea's intelligentsia by killing civil servants and intellectuals. On 20 August, General MacArthur warned North Korean leader Kim Il-sung that he was responsible for the KPA's atrocities. By September, the UN Command controlled the Pusan perimeter, enclosing about 10% of Korea, in a line partially defined by the Nakdong River."?
Answer:
What partial definition was created by Nakdong?