The Wilson Center's Cold War International History Project has more on the North Korea's role in the Korean War. If interested, check out this website.
I was especially interested in Shen Zhihua's article (the second piece), which describes the Sino-North Korean conflict during the War. He talks about that the Chinese leadership did not recieve notification of the attack on South Korea on June 25, and they learned of it from foreign news services; China intended to assist North Korea even before the Korean War began, but the North Korean leadership steadfastly refused to accept Chinese offers of assistance until forced to do so because of the UN advance across the 38th parallel.
Opposite to my thinking.