What about South Korea and Japan? The US should be involved in these areas.
I assume you mean the Korean war. They were invited there. Also it was a UN mission.
As for Japan, that was in 1945. It was 75 years ago. Virtually every example of the US invading or triggering regime change has been a disaster since then. Vietnam, Afganistan and Iraq are great examples of military intervention going horribly wrong.
There are also tons of examples of America trying to use subterfuge or influence to control other countries, that usually goes wrong too.
Guatamala, Cuba, Iran etc
Basically, America needs to learn that they can't control or rule over the rest of the world. It ends badly every time they try.