Why was the zimmerman telegram a contributing factor to the factor to the u. s declaration of war

The Zimmermann Telegram was a secret telegram that contained a message formatted in code from Germany on February 24, 1917. The telegram was for Mexico because Germany wanted to make an alliance with them against the U.S. Germany wanted to become allies so that Mexico could keep us [the U.S.] occupied in America and stay out of German territory. Germany tells Mexico that if they win, they will get some of the U.S. land that they once had back. This led the U.S. to becoming involved because the Germans and Mexicans planned a secret alliance against us.Thanks.

Andrei karlov was the russian ambassador