Isolationism refers to America's longstanding reluctance to become involved in European alliances and wars. Isolationists held the view that America's perspective on the world was different from that of European societies and that America could advance the cause of freedom and democracy by means other than war. American isolationism did not mean disengagement from the world stage. Isolationists were not averse to the idea that the United States should be a world player and even further its territorial, ideological and economic interests, particularly in the Western Hemisphere. This means the United States didn't get involved with any relationship with other countries.
On the other hand, interventionism is a policy of non-defensive activity undertaken by a nation-state, or other geo-political jurisdiction of a lesser or greater nature, to manipulate an economy or society. This means the opposite to isolationism. The most common applications of the term are for economic interventionism, a state's intervention in its own economy, and foreign interventionism, a state's intervention in the affairs of another nation as part of its foreign policy. The political government of a state decide actions of foreign intervention and foreign policy. Political interventionism can include methods such as sanctions on a foreign economy or international trade with similar results to protectionism, or other international sanctions through international cooperation decisions guarding international law or global justice. Political support or political capital, such as nationalism or ethnic conflict also decide foreign intervention actions such as occupation, nation-building and national security policies.
