The US took all of the following actions to oppose aggressor nations before entering the war in December 1941 EXCEPT .?

Before entering World War II in December 1941, the US took several actions to oppose aggressor nations, such as providing aid to Allied nations through programs like Lend-Lease, imposing economic sanctions on Japan, and supporting Britain through military supplies. However, the US did not engage in direct military conflict or declare war against any aggressor nations until the attack on Pearl Harbor. This distinction highlights that while the US was involved in diplomatic and economic measures, it had not yet committed to military intervention prior to December 1941.