In March 2011, international reaction to Gaddafi's military crackdown culminated in a United Nations resolution to enforce a no fly zone in Libya. Obama authorized U.S. forces to participate in international air attacks on Libyan air defenses using Tomahawk cruise missiles to establish the protective zone. On March 18, 2011, Obama addressed the nation from the White House announcing U.S. military strikes with NATO forces against the Gaddafi regime With coalition support, the rebels took Tripoli the following August. The Libyan campaign culminated in the toppling of the Gaddafi regime, but Libya experienced turmoil in the aftermath of the civil war. Obama's intervention in Libya provoked criticism from members of Congress and ignited a debate over the applicability of the War Powers Resolution. The intervention was led by NATO, but Sweden and three Arab nations also participated in the mission. Obama authorized the firing of 110 Tomahawk cruise missiles against targets in Libya, in response to regime actions against rebel forces, to enforce the UN no-fly zone. Controversy arose over whether Obama's use of military force without prior congressional approval was constitutional, with comments by Yale law professor Jack M. Balkin and "Salon.com" columnist Glenn Greenwald.