Considering this was before the Sino-Soviet split and that the USSR held veto rights I'm surprised they don't have a more prominent position when it comes to discussing the war. As a tag on question, what did they actually do to help North Korea after the invasion force landed and did the nature of this help change from that prior to the international involvement in the war?
It's been a while since I read it but based on Max Hastings' excellent The Korean War:
In October 1949, the Chinese Civil war which had been raging on and off since 1927, ended with Mao Zedong declaring victory in Beijing. However, the Communist forces had failed to completely eliminate their Kuomintang enemies under Chiang Kai-Shek, who retreated to the island of Taiwan and maintained that they remained the legitimate government of all of China, temporarily housed in Taipei.
Nonetheless, the UN continued to recognise the Taipei government as the representatives for China rather than recognising Mao as the new Chinese leader. In fact, it wouldn't be until 1971 that the UN expelled the Republic of China (ie Taiwan) and admitted the People's Republic in its place.
In protest at this, the USSR boycotted the UN for a while, and it was during this boycott that Resolution 82, demanding that North Korea withdraw from the south and threatening military action if not, was put forward.
In the event, of 5 permanent and 6 non-permanent members, 9 voted in favour, one (Yugoslavia) abstained and one (USSR) was absent. The Permanent members have a veto and it is widely assumed that had the USSR been present they would have vetoed the action.
In terms of Soviet involvement in the war, they were careful to keep it at arm's length; with US troops on the ground in Korea, if Soviet troops also took to the field you would end up with a shooting war between two nuclear powers and nobody wanted that at all.
Soviet assistance to North Korea initially took the form of sending medical and material supplies, but their main contribution was to the fledgling North Korean Air Force which, at the outset of hostilities in 1950 consisted of a handful of biplane trainers. The Soviets supplied state-of-the-art MiG-15 fighters and pilots - officially just to train the Koreans but in reality flying combat missions as well.
It is almost certain (unless definite evidence has come up since Hastings wrote his book) that there were indeed air-to-air combats between American and Russian pilots but to prevent escalation it suited both sides to stick to the official version, that the pilots were North Korean, not Russian.