Answer:
The answer is Mao was worried about his border with North Korea being in jeopardy.
Step-by-step explanation:
Mao Zedong was characterized as the leader of the Communist Party of China and the People's Republic of China. Thanks to him the Communist Party took power in China in 1949, and involved China in the Korean War because China warned that it would react if the UN military forces crossed the border with the Amnok River, but Mao waited for the Soviet help before attacking. One of his phrases about Korea is famous: "as close as lips and teeth"