According a recent article in Foreign Policy in Focus–The Lasting Significance of Kwangju-President Jimmy Carter:
gave tacit approval to the Korean military to use force to put down student and worker protests, while warning generals not to use excessive force. Then, when the Kwangju citizens fought back against military atrocities, the same officials approved the dispatch of Korean troops under U.S. command to put down the rebellion. Carter’s actions helped pave the way for nearly eight more years of repressive military rule in South Korea and triggered a wave of anti-American feeling throughout South Korea that persists to this day.
I encourage you to read the entire article.
In supporting a government that massacred its citizens on the streets, the US was on the wrong side of history. South Koreans eventually won Democracy just a few years later; other countries whose citizens were killed on the streets may have to wait two or more generations.