What if a Chinese officer discovered his wife and daughter's defection to the west and decided to join them in their new life (As if in OTL the wife managed to hide it from him until she and the daughter escaped China)?
The Chinese officer brought information regarding Chinese upcoming participation in the Korean war and the fact that they are going to secretly cross the Yalu River on 19 October to the CIA officer who was in charge of moving them to the US. This highly important information was moved forward and change history overnight.
After a very long debate it was decided to ambush the Chinese. Tanks were hidden near the river and military strategists were brought on board to deal with this new threat to success in the Korean war.
The Korean/Chinese war and increased tension on the Cold war as a result
The US forces attacked the Chinese on Yalu river with all they got including massive bombing and after a while managed to make the Chinese fall back to the China. As the Chinese moved back they yelled we'll kill you all!. The Soviets were angry that the Chinese couldn't help their comrades and urge them to declare war on America. Many historians agree that only the close relationship between Stalin and Mao made the Chinese to ultimately declare war. The UN forces in Korea agreed to help and also declared war on China, the soviet remain neutral officially but they sent massive weapons, fuel and food to help the Chinese just as they did in north Korea. In a short while, the war in China became static as the Chinese used their hard terrain to stall UN forces and higher numbers. It almost seemed as whole of China fought the west and the situation looked bleak. with no under option, the soviet being officially neutral and under massive pressure from General of the Army Douglas MacArthur, Truman launched two nuclear strikes on China and one on north Korea. Two bombs were dropped deep in Chinese cites (Beijing and Chongqing) and the last one was dropped in was dropped in a military base on the North Korean/Chinese Border. Both China and Korea declared ceasefire and agreed to end the war on the western terms. North Korea and south Korea were united in a democratic country which were monitored by the UN until 1972 and China was under martial law of the US (like Japan post WW2) which was designed to end in 1959. The Soviets became more and more working in order to make their sphere of influence more dominant than the American one as many taught when an all out war between NATO and the Warsaw Pact (signed on 14 May 1955) would start.