How did the unrestricted submarine warfare lead the US into world war 1?

Unrestricted submarine warfare, primarily practiced by Germany, involved attacking merchant and passenger ships without warning, aiming to cut off supplies to the Allies. This aggressive strategy led to the sinking of neutral ships, including the Lusitania, which resulted in American casualties and heightened public outrage. The repeated violations of neutral rights and the threat to American lives and commerce ultimately pushed the U.S. government to declare war on Germany in April 1917, marking a significant turning point in World War I.