I. M. Esperto wrote "I Have Control - I have no idea why Wilson entered the USA into WWI. I think it was unjustified, and a mistake."
On Januart 17th 1917 "Room 40" of British Naval Intelligence intercepted and decoded a telegram from the German Foreighn Minister Zimmermann to their Ambassador in Washington. This showed that Germany was attempting to initiate an alliance with Mexico and Japan against America. It was eventually passed to Wilson who had no alternative but to enter the War.
"WE INTEND TO BEGIN UNRESTRlCTED SUBMARINE WARFARE ON THEE FIRST OF FEBRUARY. WE SHALL ENDEAVOR IN SPITE OF THIS TO KEEP THE UNITED STATES NEUTRAL IN THE EVENT OF THIS NOT SUCCEEDING, WE MAKE MEXICO A PROPOSAL OF ALLIANCE ON THE FOLLOWING BASIS: MAKE WAR TOGETHER, MAKE PEACE TOGETHER, GENEROUS FINANCIAL SUPPORT, AND AN UNDERSTANDING ON OUR PART THAT MEXICO IS TO RECONQUER THE LOST TERRITORY IN TEXAS, NEW MEXICO. AND ARIZONA. THE SETTLEMENT IN DETAIL IS LEFT TO YOU.
YOU WILL INFORM THE PRESIDENT [OF MEXICO] OF THE ABOVE MOST SECRETLY AS SOON AS THE OUTBREAK OF WAR WITH THE UNITED STATES IS CERTAIN AND ADD THE SUGGESTION THAT HE SHOULD, ON HIS OWN INITIATIVE, INVITE JAPAN TO IMMEDIATE ADHERENCE AND AT THE SAME TIME MEDIATE BETWEEN JAPAN AND OURSELVES.
PLEASE CALL THE PRESIDENT'S ATTENTION TO THE FACT THAT THE UNRESTRICTED EMPLOYMENT OF OUR SUBMARINES NOW OFFERS THE PROSPECT OF COMPELLING ENGLAND TO MAKE PEACE WITHIN A FEW MONTHS. ACKNOWLEDGE RECEIPT.
ZIMMERMANN."
All this at a time when German was supposedly "negociating" with the USA to maintain peace!
Get a copy of "The Zimmermann Telegram - How the USA Entered the Great War" by Barbara Tuchmann (1958) and read it - then decide whether it was "..unjustified and a mistake".