Hitler targeted Jews and others he deemed "undesirable" for persecution in Germany. His racist beliefs led him to blame Jews for Germany's problems after World War 1. Persecution began with economic measures like business boycotts but escalated to violent attacks and mass imprisonment in concentration camps. Hitler's "Final Solution" was the genocide of all Jews, which resulted in the deaths of millions in death camps through gas chambers, torture, starvation and disease. While Allied leaders were aware of Nazi atrocities, they were slow to take action to stop them. After the war, survivors found refuge in places like the new state of Israel and the U.S., which became a staunch Israeli ally.