WWI that started a century ago went without direct participation of the USA for a long time. Country with great economic capacity that gained political weight on the international arena proclaimed and adhered to a long-term neutrality by trading with countries at war and making profit.
Government propaganda on all levels demonstrated determination of the USA to the officially declared commitment, although opposition press and European media were making fun of Washington’s politics. After a while anti-German sentiments in American society took over, in April 1917 the United States joined the war. Well, at least we have amusing posters and postcards from back then.