Why did the United States enter World War I?

The reason the United States entered World War I is primarily linked to its commitment to assist its Allies, particularly Britain and France. As the war progressed, the conflict in Europe had significant repercussions on American interests and international stability. The U.S. aimed to support these nations due to existing alliances and a shared interest in defeating the Central Powers.

Additionally, there were various factors at play, including the naval warfare tactics employed by Germany which threatened American shipping, and the interception of the Zimmerman Telegram that revealed Germany's proposal for a military alliance with Mexico against the U.S. These actions fostered a sense of urgency to protect both American sovereignty and the interests of its allies.

While expanding territory and promoting democracy were part of the broader context of U.S. foreign policy, the immediate catalyst for entering the war was the desire to support allied nations and maintain a balance of power in Europe. The notion of responding to a direct attack, while it applies more to World War II, wasn't the defining factor for U.S. involvement in World War I, as there was no direct military assault on American soil that precipitated entry into the conflict. Hence, assisting allies was the primary motivation behind the U.S. decision to join the war.