This question is difficult to answer as the US involvement in the Holocaust was one of isolationism, ignorance, denial, or anti-Semitism depending on what you read and which you believe. One action of the US government was to deny entry to a ship full of Jews trying to escape from Germany to a safe haven in the US. We sent them back to Germany where almost all of them died. One comparison that would probably fit your criteria would be the US keeping to its policy of isolation during the Spanish Civil War in the late 1930s. We as a country stayed on the sidelines while many people died and the Spanish government turned upside down.