How did German attacks on United States shipping change America's policy of neutrality?

Germany’s attacks on American shipping changed the policy of neutrality that the United States was following before it entered World War I. The United States remained neutral when World War I began. This meant the United States was allowed to trade with any country, including countries that were at war. When Germany began to sink American ships, the United States warned Germany to stop. In the Sussex Pledge, Germany agreed to stop sinking American ships. As a result, the United States remained neutral.
However, Germany broke this pledge in 1917. Germany began to sink American ships. As a result of this and other factors, the United States joined World War I on the side of the Allies. Germany believed that victory was near, and Germany was convinced it would win the war before the United States could become a major factor in the war. Germany terribly miscalculated based on this belief.
https://2001-2009.state.gov/r/pa/ho/time/wwi/82205.htm

https://www.history.com/this-day-in-history/germans-sink-american-merchant-ship