This is not a defensive war, but a preemptive one against Germany, coordinated by the Republicans under President William McKinley. Notable politicians supporting him were Theodore Roosevelt (Secretary of Navy), William Taft (Governor of Philippines), John Hay (Secretary of State), Henry Adams, and Henry Cabot Lodge (Senator from Massachusetts). All of them were aware of the rise of Germany and thus decided to initiate an attack against it.
Russo-Japanese War; victory for Japan
Election of Woodrow Wilson
WWI began, triggered by the assassination of Franz Ferdinand by a Serb.
Turning point of WWI.
Bolshevik Revolution, with Lenin promising to provide the Russians with land, bread, and peace.
Russia left the War.
US entered the War.
US as a war spectator
Although the presidents in both WWI and WWII were Democrats, neither of them led the US into the wars, unlike the Republicans who led the US into the Spanish-American War in 1898. It is a Republican program to make America a global power.