The document presents two cases for why the US entered World War 1, with multiple perspectives within each case. Case 1 examines US military advancements, including the growing military build-up and implementation of the draft. Case 2 looks at threats against US neutrality, such as attacks on merchant ships by German submarines and the Zimmerman Telegram proposing a German alliance with Mexico against the US. The document provides primary sources representing different viewpoints and asks the reader to decide the primary reason for US entry into the war.