Nothing. There our Allies
No, the U.S. and South Korea were allies against North Kores.
The Korean War (Korean Conflict)
South Korea
During the Korean War, the US supported South Korea and their fight against communism. They have supported Korea and their endeavors since.
The US is not permitted to patrol North Korea, nor do they. The US military does however have military bases in south Korea as part of a treaty to protect them against a possible attack by North Korea.
The US wanted to cease the spread of communism in the East.
US & UN (and South Korea, if they weren't part of the UN) against Red China & North Korea.
In the Vietnam War the US opposed the invasion of South Korea by North Korea. The fighters from North Korea, who used guerilla tactics, were known as the Viet Cong.
Ahn Ho-Young is the Ambassador to the US for South Korea.
They invaded South Korea, the people are starving and have famine. No freedom a basic US ideal, North Korea's diplomacy is unpredictable and radical. and if you want to be more specific with your question please do.
South Korea
No their totally against each other North Korea threatens to destroy South Korea and their hard work.