This would include pilots in NE China who did not fight and the AAA guys who may or may not have been south of the Yalu. The Soviets certainly supplied critical heavy weapons, railroad equipment and training to both North Korean and Chinese forces. I don't know how you feel about letting the former enemy march, but they certainly weren't on the UNC's side. Most of them served with the 64th Fighter Aviation Corps as MiG pilots, crews, antiaircraft gunners, or support personnel. A handful served as advisors to the North Koreans and Chinese.
Direct casualties are hard to say.