38th parallel : line of latitude marking the border between north Korea and south Korea .
Demilitarized zone ( DMZ) : area on either side of the border between north Korea and south Korea where troops and weapons are not allowed .
Communism : economic system that favors public or government ownership of business . A person who supports communism is a communist .
Containment: U. S. Policy after world war II that focused on stopping the spread of communism around the world. Counterattack : fighting begun to move forward against an enemy that had been advancing.