Answer:
It was the Korean War that changed the American approach to Japanese economy.
The Korean War, which took place only a couple of years after the end of WWII (WWII ended in 1945, and the Korean War started in 1950) changed how the US approached Japan in general given that Korea had been under Japanese rule for 35 years. This war happened between North Korea and South Korea which were initially divided in 1949 in order to bring them back together again.