The Chinese completely lost naval and superiority, had barely any armor, almost none existent anti armor weapons, were marching on foot why the UN forces were mechanized and their supply lines in a terrible state at one point barely able being able to feed them.
I hope you get an answer that directly addresses your question, but in the interim here's an answer written by u/Anekdota-Press addressing the following question:
"Chinese textbooks state the Korean War was started by the South as a springboard for US invasion of China. I have learned this to be false...but how can I REALLY know?"
The response goes into some detail about the disposition of forces that you may find interesting, mainly the following:
...[W]ar broke out when the South Korean military was unprepared for war. At a time when US military strength in the ‘Far East Command’ was likewise extremely low and mostly unprepared for war. US force levels were steadily reduced from the end of WWII. In 1947 MacArthur commanded over 300,000 troops in the Far East Command, but by June 1950 this had dwindled to only 108,500 army troops. Shrinking troop levels were accompanied by a near total lack of investment in material and weapons. Army postwar procurement was almost entirely limited to “food, clothing, and medical supplies” with the army expected to rely on aging stocks of leftover WWII weapons.
MacArthur in 1947 had commenced ‘Operation Roll-Up’ to refurbish US equipment which had been left to rot at bases all around the Pacific when the war ended. This did lay the groundwork for the repair and production of military equipment in Japanese factories. But the program was not complete by the deadline of June 30, 1950. At which point “an estimated 80% of the army’s 60-day reserve of armament equipment was unserviceable.”Far East command received no new vehicles, tanks, or other equipment between the end of WWII and the outbreak of the Korean War. Crucial equipment, everything from recoilless rifles to heavy trucks, were present in low numbers and 50-90% of stocks were unserviceable.The South Korean military had no tanks and “virtually no air force”. In contrast to North Korea's 150 medium tanks and small tactical air force. The North had a 3:1 advantage in artillery and tens of thousands of experienced troops who had fought in the Chinese Civil War. South Korea also failed to make any preparation for defense in depth or a layered supply system. There were no plans for a fighting retreat or destruction of supplies in the event of a retreat. Accordingly, once the invasion occurred South Korean military supply and communication broke down in the early stages of the war.
The specific disposition of South Korean forces when war broke was also highly disadvantageous. Units were under-strength due to farming season furlough. Even more soldiers and officers departed for the weekend because an existing alert order was lifted. Huge numbers of officers were away from their posts in Seoul sleeping off the effects of a celebratory banquet. Others were abroad in the US or Japan. The head of the US advisory group in Korea had been reassigned and his temporary replacement was in Japan. Of the four divisions posted on the border, only four regiments and one battalion were actually stationed on the line. This utter unpreparedness is seen in the disastrous retreat of South Korean forces south. Or in incidents such as the premature destruction by S. Korean forces of the bridge on the Han River which trapped several friendly units on the other side.