Isolationism.
President James Monroe has instituted a policy of US withdrawal from Europeans. This was because, according to Monroe, Europe intended to resume the colonization process.
The president's ideology became known as The Monroe Doctrine, according to which "the American continents, by virtue of the free and independent condition they have acquired and preserved, can no longer be considered in future as susceptible to colonization by any European power."
It was in this context that Monroe said his celebrated phrase: America for the Americans.
