In the episode the 4077th finds shrapnel in South Korean villagers. They presume that a US military aircraft must have bombed the SK village. Nobody considered this possibility-- that when Chiang Kai-Shek's nationalist troops defected to Mao's communist side in China in 1949 the troops took their US-made weapons with them ( and they actually did).Or even the possibility just that it was a confiscated American plane a North Korean crew was flying!

PS Kim II Sung started the whole Korean War and was never mentioned on this TV show ( see my postings).