The United States responded to the sinking of the Lusitania by entering World War I alongside the Allies.
When German U-boats sank the Lusitania, the United States responded by entering World War I on the side of the Allies. The sinking of the Lusitania, which resulted in the loss of American lives, shifted American public sentiment towards entering the war against Germany. This event, coupled with Germany's announcement of unrestricted submarine warfare, led to the United States declaring war on Germany in April 1917.
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