Why are we still dedicated to defending South Korea if the Cold War ended in 1989?

if your talking about why USA  defends korea then ir because On June 27, 1950, President Truman ordered U.S. forces to South Korea to repulse the North's invasion. “Democrats needed to look tough on communism,” Kim says. “Truman used Korea to send a message that the U.S. will contain communism and come to the aid of their allies

maybe #3? try that i think its correct