Why did the zimmerman note upset the American public?

The Zimmermann Note upset the American public because it revealed Germany's proposal to Mexico for a military alliance against the United States during World War I. The note promised Mexico the territories of Texas, New Mexico, and Arizona if Germany won the war. This revelation fueled anti-German sentiment and increased calls for U.S. involvement in the conflict, ultimately contributing to America's decision to enter the war. The perceived threat to national security and sovereignty heightened public outrage and rallied support for the war effort.