Why did Zimmerman note outraged American public opinion?

The Zimmerman Note outraged American public opinion because it revealed Germany's attempt to incite Mexico to join the war against the United States during World War I. The telegram suggested that if Mexico allied with Germany, it would help Mexico regain territory lost to the U.S., including Texas, New Mexico, and Arizona. This perceived threat to American sovereignty, coupled with the British interception and publication of the note, fueled anti-German sentiment and contributed to the U.S. decision to enter the war. The combination of betrayal and a direct challenge to national security stirred public outrage and rallied support for intervention.