In the 1991 Gulf War, the almost immediate suppression of Iraq's air defenses, along with the combination of new real-time surveillance systems and precision attack capabilities, gave air power an edge it had never before had. The introduction of low observability ("stealth") technology and the use of space-based assets for navigation and targeting, such as GPS, have further enabled air power, properly used, to achieve strategic objectives almost from the earliest moments of a joint military campaign. But geography continues to limit the ability of air power to meet all demands of the joint force commander. The generally open terrain of the Persian Gulf area provided a significant contrast to the more challenging terrain of Bosnia and Kosovo. And although air power would be the key to success in any war that might erupt in Korea, it would not by itself be able to halt a North Korean ground invasion. The U.S. Air Force is now moving to establish "Air Expeditionary Forces," built out of pieces from various units and available to deploy on short notice to hold the line until more sustained combat operations could begin.