In recent weeks, several Republican presidential candidates have hinted at vague strategies for dealing with the threat posed by the Islamic State. They all have in common the “if only” factor: “If only President Obama had kept a residual military force in Iraq after 2011, then the Islamic State would not be a problem today.” This argument ignores the inconvenient fact that it was the Bush administration and the Iraqi government together that decided to withdraw all U.S. combat forces from Iraq by 2011. Critically, U.S. military forces were no longer welcome in Iraq.

It is worth remembering that the 2008 Status of Forces Agreement signed by the Bush administration was titled an “Agreement between the United States of America and the Republic of Iraq on the Withdrawal of United States Forces from Iraq and the Organization of Their Activities during Their Temporary Presence in Iraq.”