The United States entered World War I after which German policy intensified attacks on ships?

• A. Neutrality after 1917
• B. Unrestricted Submarine Warfare
• C. Zimmermann Telegram
• D. Economic sanctions

Answer: (B)

Unrestricted submarine warfare by Germany is the factor that most directly pushed the United States toward entering World War I. Germany decided to sink ships bound for Britain and other Allied nations without warning, using U-boats to block supplies. This policy meant American lives and commercial interests were at direct risk and disrupted trade with the Allies, making it clear that the war affected U.S. security and economic interests. When Germany resumed this aggressive submarine campaign in 1917, American public opinion and the government moved toward joining the conflict to safeguard access to trade and to defend neutral rights. While events like the Zimmermann Telegram influenced support for entry, the immediate cause was Germany’s policy of attacking ships without warning.