Question

What are the two causes for the United States to join World War I? *

Answer 1

Answer:

Well, Reintroduction of Unrestricted Submarine Warfare .

Germany resumed unrestricted submarine warfare in 1917. Knowing they risked provoking the United States into joining the war, Germany gambled on defeating the British before the US had a chance to mobilization. Good Luck!

$^{Itsbrazts}$