Zimmerman note outraged Americans by proposing what?

The Zimmermann Note outraged Americans by proposing a secret alliance between Germany and Mexico during World War I. In the note, Germany promised to support Mexico in reclaiming territories it had lost to the United States, including Texas, New Mexico, and Arizona. The revelation of this communication in early 1917 intensified anti-German sentiment in the U.S. and contributed to the decision to enter the war against Germany.