Attack on Pearl

Hello again. Another great main starter question and there are a lot of ways we'll attack it but I'd like to get your thoughts on the specific US involvement here. There were a series of events that led to the attack at Pearl, including both specific events between Japan and the US and events in Europe that all culminated with the US entry into the war. Guys, what might be one of those events that involved the US in the 1930s before the war started in 1939?