What were two reasons that america began to mobilize for war against the central powers war by 1917?

The Zimmermann Telegram and the sinking of American ships and the British-owned Lusitania (with 128 American lives perished) urged America to mobilize for war against the Central powers. The Zimmermann Telegram was sent by German Foreign Minister Arthur Zimmermann to Mexican Government to suggest that they should declare a war against the US to get back the territories they have lost in the Mexican-American War. However, the British intercepted the telegram and immediately informed the US Government.