How was the us morally economically and politically jusified in entering ww1?

Morally: Unrestricted submarine warfare by Germany resulted in the deaths of many Americans, including over one hundred U.S. citizens traveling on Lusitania.

Economically: Trade with Great Britain was being negatively affected by German intervention. Entering the war would create a strong U.S. foothold in Europe.

Politically: The Zimmerman Telegram, which suggested that Mexico should wage war against the U.S., provoked America to enter.