The actions and decisions during the cold war were the consequences of this theory.
Explanation:
Domino theory suggests fear and says that if a single country can attack and seize another country, then it has the potential to attack more countries.
For the USA: Since NK was communist and supported by Joseph Stalin of Soviet. America got worried that NK's win over South may help Soviet in spreading its communist ideology.
For China: When NK was invaded with the help of USA. China got worried that this victory may lead the US army towards them.
