Truman's Democratic administration pulled our troops out of South Korea too soon, in the late 1940's.
As a result, Kim il-Sung, the Communist dictator in North Korea, easily conquered most of South Korea in 1950.
In just 30 months, Truman sacrificed 30,000 American lives in order to win back South Korea, which we never should have abandoned in the first place.
Excellent point, syriacus.
One of those inconvenient truths.