Cause). By 1989 Germany was nearing reunification and the Cold War was coming to a close. Army leadership reacted by starting to plan for a reduction in strength. By November 1989 Pentagon briefers were laying out plans to reduce army end strength by 23%, from 750,000 to 580,000. A number of incentives such as early retirement were used. 1990s In 1990, Iraq invaded its smaller neighbor, Kuwait, and U.S. land forces quickly deployed to assure the protection of Saudi Arabia. In January 1991 Operation Desert Storm commenced, a U.S.-led coalition which deployed over 500,000 troops, the bulk of them from U.S. Army formations, to drive out Iraqi forces. The campaign ended in total victory, as Western coalition forces routed the Iraqi Army. Some of the largest tank battles in history were fought during the Gulf war. The Battle of Medina Ridge, Battle of Norfolk and the Battle of 73 Easting were tank battles of historical significance. After Operation Desert Storm, the army did not see major combat operations for the remainder of the 1990s but did participate in a number of peacekeeping activities. In 1990 the Department of Defense issued guidance for "rebalancing" after a review of the Total Force Policy, but in 2004, USAF Air War College scholars concluded the guidance would reverse the Total Force Policy which is an "essential ingredient to the successful application of military force". 21st century On 11 September 2001, 53 Army civilians (47 employees and six contractors) and 22 soldiers were among the 125 victims killed in the Pentagon in a terrorist attack when American Airlines Flight 77 commandeered by five Al-Qaeda hijackers slammed into the western side of the building, as part of the September 11 attacks. In response to the 11 September attacks and as part of the Global War on Terror, U.S. and NATO forces invaded Afghanistan in October 2001, displacing the Taliban government. The U.S. Army also led the combined U.S. and allied invasion of Iraq in 2003; it served as the primary source for ground forces with its ability to sustain short and long-term deployment operations. In the following years, the mission changed from conflict between regular militaries to counterinsurgency, resulting in the deaths of more than 4,000 U.S. service members (as of March 2008) and injuries to thousands more. 23,813 insurgents were killed in Iraq between 2003 and 2011. Until 2009, the army's chief modernization plan, its