Answer:
The factors that pushed the United States to enter the war are: Direct attack on US ships, Germany's attempted alliance with Mexico and A desire to preserve the world Democracy.
Step-by-step explanation:
At the beginning of world war 1, The US President at the time(President Woodrow Wilson), proclaimed the US will remain neutral during the war and not participate. The US officially entered the war on April 17, 1917. This is as a result of direct attack on United States ships, Germany's attempted alliance with Mexico and the desire for the US to preserve democracy.
The United States took decision to join the conflict after The sinking of the Lusitania ship by a German U-boat in the year 1915 which resulted in the death of 128 Americans and about 2000 people as well as the Zimmerman telegram which threatened the alliance between Germany and Mexico.