The Offshore Balancing Thesis Reconsidered: Realism,the Balance of Power in Europe,and America's Decision for War in 1917

According to John Mearsheimer, the United States entered the First World War because the Wilson administration believed the Triple Entente was on the verge of defeat. As a result, he claims, the Americans entered the war to prevent Germany from becoming a regional hegemon in Europe. A careful and targeted examination of the relevant primary sources, however, demonstrates that Washington was largely unaware of the plight of the Allied powers in the spring of 1917; therefore, the argument that the United States was acting as an offshore balancer at this time is unconvincing. This article shows that unit-level factors and statecraft can play a larger role in international relations than structural realist theory allows and makes an empirical contribution to the World War I literature by demonstrating that balance of power considerations were not a major factor in the Wilson administration's decision for war.