 Following the sinking of the on 7 May 1915 and subsequent public outcry in various neutral countries, including the United States, the practice was withdrawn.However, Germany resumed the practice on 1 February 1917 and declared that all merchant ships regardless of nationalities would be sunk without warning.This outraged the U.S. public, prompting the U.S. to break diplomatic relations with Germany two days later, and, along with the Zimmermann Telegram, led the U.S. entry into the war two months later on the side of the Allied Powers.