I want to know the answer to the following question:
What tactics of the PVA were US and ROK troops not prepared to handle?
All the background I'm provided with is that "The UN Command retreated; the U.S. Eighth Army's retreat (the longest in US Army history) was made possible because of the Turkish Brigade's successful, but very costly, rear-guard delaying action near Kunuri that slowed the PVA attack for two days (27–29 November).". Is that enough to answer the question?
Answer: no