PLA surprise attack gained some success, but US quicly found out how to beat that tactic, and at the end of Korean war, US beat up PLA badly, made Mao keep his mouth shut cos PLA didnt know any more better tactic to keep fighting. Thats so pathetic ending for PLA in Korean war .
Google trans
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A series of subsequent attacks slowly repulsed Chinese and North Korean troops such as the Courageous and Tomahawk operations, a combination of infantry and air force capturing communist forces between Kaesong and Seoul. United Nations forces continued their advance until they reached the Kansas line, a few miles north of the 38th parallel.
However, in April 1951, China launched a fifth phase offensive. This was a major effort with the participation of three legions (up to 700,000). The main punch hit the US Army Corps I, but fierce resistance in the battles at the Imjin and Kapyong Rivers blocked the Chinese army's advance in the northern defense line of Seoul.
Another subsequent Chinese offensive in the central region against the X Corps and South Korean forces on May 15 also achieved initial success, but on May 20 the attack stopped. The 8th Army counterattacked and by the end of May recaptured the Kansas line.
The UN decision to halt at the Kansas Line, just north of the 38th parallel, and not to continue its offensive operations into North Korea, pushed the war to a standstill, a prime example of the the rest of the conflict.
https://vi.m.wikipedia.org/wiki/Chiến_tranh_Triều_Tiên