Question

After remaining neutral since the war's start, the United States entered World War I because Germany continued to wage unrestricted submarine warfare, which resulted in the sinking of American ships. The interception of the Zimmerman Telegram, in which Germany petitioned Mexico to join against the US, was another major factor. On April 6, 1917, Congress decided to declare war on Germany.

Answer 1

Actually the sinking of the Americans ships was justified for Germany as they were trying to hind down supply ships for britain and the lusatannia was one that carried weapons to Britain. The United States of America knew that so they planned a war against Britiain but it didn't matter as then Germany sent the Zimmerman and payed for it by getting on uncle Sam's bad side.