The U.S. would not take part in any foreign wars.
The American continents were not subject to future European colonization.
The Monroe Doctrine was issued in 1823 and was the leading foreign policy for the US until entering imperialism and the world wars.
The Monroe Doctrine was issued to protect the independence of the US and newly emerging independent countries from European colonial control. The goal of the plan was to establish zones of interest--the US would take care of the western hemisphere and Europe would focus on the eastern hemisphere. The US agreed to stay out of foreign wars as long as Europe agreed to keep their hands off lands in the Americas. The US stated they would view a grab for land in the Americas by a European country as a hostile act that could be countered with military action.