Why was the battle of korea an important cold war event?

The war cost more than 2 million lives and ruined the economy of Korea for twenty years. It also had implications for a wider conflict, the Cold War. The main protagonists of that political, economic, military and ideological contest, the Soviet Union And the United States of America, intervened in the Korean War. The Soviet Union and its ally China backed North Korea, while the United States gathered an alliance under the auspices of the United Nations (UN) to support the south

( I don't know if this is 100% correct but...)