In 1945, under Truman, the US freed S. Korea.
In 1948-49, under Truman, the US military budget was cut to the bone and troops were withdrawn from an unstable and militarily weak S. Korea.
In 1950, N. Korea invaded S. Korea
In 1950, Truman sent troops back to S. Korea to rewin it's freedom.
30,000 Americans died in Korea in the 30 months remaining of Truman's presidency. (7/1950 - 1/1953)
During the Korean War, under Truman, the military draft was ramped up and the strictest wartime censorship in memory was put in place.
Odds are, there would not have been a Korean War if our troops had remained in Korea for a longer time, as they did in Japan and Germany
The only winners were the Japanese--the Korean War has been characterized as a Marshall Plan for Japan (since US spending during the war poured so much money into Japan).
But Republicans controlled both houses in the 80th Congress (1947-49) which includes one of your mentioned years so you can't blame Truman entirely.
Republicans | Democrats | |
House | 246 | 188 |
Senate | 51 | 45 |
It's interesting that the Republicans also controlled Congress from '94 and helped Clinton spend the "peace dividend" and slash our military.