"The United States is still at war in Iraq – on paper, at least," Defense One points out.
"Two years after U.S. troops withdrew from Iraq, the authorization for the use of military force that was passed by Congress in late 2002 is still in effect. A group of bipartisan senators introduced a bill that would repeal that law, officially ending the war in Iraq. The Authorization for Use of Military Force in Iraq was not a declaration of war. If it's repealed, Congress will have to approve any new military action in Iraq."
Foreign Policy notes the legislation has the support of the White House.