Answer:
for ww1: Germany's resumption of submarine attacks on passenger and merchant ships in 1917 became the primary motivation behind Wilson's decision to have the U.S enter ww1
ww2: after the attack on pearl harbor the U.S declared war on Japan and following a few days later nazi Germany declared war on the U.S causing U.S to enter ww2 against the axis powers
Explanation:
i not sure which war you meant so i put both. hope this helps
