Yes. Im not positive about soviet troops(though there is convincing evidence that the UN air force was fightng soviet pilots), but the Battle of Chosin Reservoir is very popular in the USMC mythos. The 1st Marine Division, along with several Army units and i think a couple British, were completely encircled by veteran(contrary to popular belief, Chna didnt rely on human wave tactics. After nearly a decade at war with themselves and the Japanese, they had very experienced troops and commanders ) chinese troops twice their number. In response, the US marines fought their way out, inflicting heavy casualties on the Chinese troops and managed to prevent their complete destruction. Two of the most repeated quotes in the Corp were coined in that battle: "Retreat, hell! We're just advancing in a different direction!" And "Theyre all around us. We got them right where we want them."
In fact, the intervention of Chinese troops is what lead to the situation today. Despite some devestating setbacks in the beginning of the war leading to the near takeover of south korea by northern troops, NATO forces had nearly ran completely over NK and i believe actually made several accidental incursions into Chinese territory(ill have to get my books out to check.) Thr chinese then intervened, and pushed NATO back to the border.
I'm gonna attempt to answer this question. I know the answer and will try to provide sources, but I'm not academically trained as an historian and don't really have access to a lot of them. I am a huge military history nerd and love this stuff, but gotta maintain quality. So mods, if this answer isn't properly or adequately sourced (or just wrong) and you gotta delete it, I understand. Keep up the good work!
The short answer to your question is a resounding yes.
The long answer actually isn't really that much more complicated. So Kim Il-Sung decided that right about 1949 was a great time for an invasion. There were guerilla forces operating in South Korea against the regime (they had been reduced but that reduction had weakened the South, or so Kim believed). Stalin disagreed initially, seeing as how American forces were still stationed in Korea and there were bigger fish to fry so to speak in the ongoing Chinese Civil War. However, by early to mid 1950, Stalin believed the strategic situation had changed. The U.S.S.R. had developed nuclear weapons and the communists had won the Chinese Civil War. In light of these developments, Stalin gave the go ahead to invade with some conditions: Soviet forces would NOT engage American forces directly to avoid another world war, and only if Mao would agree to supply reinforcements in necessary. Mao, desperate for Soviet aid and support in rebuilding his war torn country and establishing his government, agreed.
So skipping forwards a bit, on 25th June, 1950, North Korea invaded South Korea, using arms and equipment largely supplied by the Soviet Union and with confidence that should reinforcements be necessary, the PLA will step up. The initial few months of the war were just a string of North Korean victories. They captured Seoul only 3 days after the invasion. The U.N. intervened, with American soldiers fighting and losing their first battle against NK forces at Osan on July 5. The NK army pushed the U.N. forces all the way back to the port city of Pusan, where they held out for several months and slowly built up their forces for a counterattack. The NK forces had performed pretty well on their own at this point, albeit against a poorly trained and equipped South Korean army and against completely unprepared U.N. forces. But now, they were basically straining their logistics to the limit, with American air and sea power making itself felt. Long story short, the U.N. forces built up until they actually outnumbered the NKs and broke out from Pusan. Meanwhile, MacArthur launched his masterstroke at Inchon on 15th September, 1950, landing roughly three divisions of soldiers and Marines far behind NK lines, capturing that city and providing the anvil to the U.N. forces out of Pusan's hammer. The NK army was almost annihilated, with only about 25-30% of the force making it back to North Korea. The U.N. forces advanced almost with impunity while North Korean, Chinese, and Soviet military commanders held emergency meetings to discuss the situation. The Chinese premier Zhou Enlai warned the U.S. that China would intervene, warning that weren't really taken seriously. However, Stalin was still committed at this point to not directly interfering against the U.N.
(Sources at the bottom of my second comment)