America's Foreign Policy Practice Exam 2025 – Comprehensive Test Prep

Submarine warfare against American ships was a significant violation that escalated tensions between the United States and Germany prior to World War I. This practice involved Germany using its U-boats to engage in unrestricted submarine warfare, which meant targeting not just enemy military vessels but also neutral ships, including those flying the American flag. The sinking of the RMS Lusitania in 1915, which resulted in the deaths of American citizens, particularly fueled public outrage in the United States and increased calls for intervention.

This policy of submarine warfare directly contravened international norms regarding neutral shipping rights and civilian safety at sea, leading to a diplomatic crisis. The aggressive nature of this military strategy highlighted Germany's willingness to disregard the territorial waters of neutral nations, thereby heightening hostilities and setting the stage for America’s eventual entry into the war.

The other options do not capture the primary triggering factor that led to direct tensions at this time. Impressments of American citizens was more of a grievance during the Napoleonic Wars; blockades of American ports were typically associated with conflicts involving Britain and were not a significant issue directly with Germany; and encouraging Native American alliances was a broader historical context that was not specifically tied to the tensions leading up to World War I.