Did the US intervene in any events leading up to their involvement in WW2? (For example, in 1933 when Germany rearms, in 1935 when Italy attack Ethiopia, or in 1937 when Japan attacks China)
The United States had very little involvement in dealing with the events leading to the start of World War II. The United States was dealing with the Great Depression. This depression was the worst economic crisis we had faced in our history. Dealing with the Great Depression was the main focus of our leaders and the American people.
The United States wanted to stay out of world affairs in the 1930s. People were upset about the findings of the Nye Committee that suggested that we entered World War I to help our businesses financially. People were concerned that only Finland repaid its debts to us from World War I. Congress passed several neutrality laws in the 1930s that prevented us from selling weapons to countries at war. One of these laws required a "cash and carry" policy if we sold non-military supplies to countries at war. These countries would have to pay cash for the supplies they bought and transport them on their own ships.
President Roosevelt was concerned about these aggressive actions and the formation of the Axis Power Alliance. When Japan invaded China in 1937, President Roosevelt gave a speech that warned the country about a growing danger if nothing was done about these aggressive actions. He believed these aggressor nations needed to be isolated. However, most Americans remained unconcerned about these events.
Thus, when Germany moved its military into the Rhineland and invaded Austria, nothing was done about these events. When Italy invaded Ethiopia, there was no action against Italy. When Japan invaded China, President Roosevelt gave a speech. There were no real actions taken by the United States to deal with these aggressive actions in Europe and Asia prior to the start of World War II.