He wanted continued control over Eastern Europe for his own benefits rather than for its people trying to influence other countries into becoming communist as opposed to democratic, this became know as the Iron curtain, the official division between USSR-communist and the US- democratic as the USSR tried to expand and gain more control.
Monroe Doctrine--This doctrine was announced in 1823 as a statement to Europe that they were no longer welcome in the Western Hemisphere as colonial holders.
Following the American Revolution and those of Mexico, Haiti, and South America, European countries had been almost completely pushed out of the Western Hemisphere. James Monroe announced his doctrine in 1823, stating the US would assist any country who had their independence threatened. This was to ensure the freedom of these new countries.