The U.S sent approximately $3 billion to help fund British and French warfare, if they lost the war, they would not be able to pay the United States back. Also, the U.S had passanger ships on the ocean that were constantly being sunk by unrestricted sub-marine warfare by the Germans, which cost the Americans millions of dollars. The sinking of the Lusitania, which was a British passenger liner had been carrying passengers from America to England and was sunk by German U-Boats, however, the liner was also thought to have been carrying weapons for allied troops. The loss of the weapons and the ammunition resulted in more money lost from the U.S, so it would only be natural for the United States to join forces with the allies.