What were the main characteristics of roosevelt's foreign policy and why was the american public bent on isolationism during the 1930s?

At the start of Franklin Roosevelt's presidency he was a strong and outspoken isolationist, as were most of the American citizens. Later in his presidency Roosevelt decide that it was more important to fight for democracy than to keep America out of foreign conflicts. Many Americans were in favor of isolationism after America's controversial involvement in World War I, a conflict which cost hundreds of thousands of American lives in Europe in the midst of a war that did not directly concern American interests.