European Security and Transatlantic Relations After 9/11 and the Iraq War

The U.S. invasion of Iraq in 2003 may have been the war to end all alliances. It was
an expression of a new assertive American interventionism that had scant regard
for global norms and institutions when these stood in the way of U.S. policy. It
ruptured the unity of NATO and led European states to reassess their relationships
with the United States.