With capability, however, has come reliance. In the words of one U.S. Air Force space official, space systems are now "woven inextricably" throughout the military capabilities of the United States and its allies. Moreover, dependency on space is increasing. By 2010, the U.S. military expects, it will need twice the capacity of its existing space-based infrastructure—in everything from the number of images per day acquired from spy satellites to the bandwidth carried by communications satellites.

Without a doubt, the exploitation of space has helped the U.S. military remain the most technologically advanced fighting force in the world. At the same time, though, it has made that force deeply vulnerable to an attack on its satellites and other space-based systems. What's more, the means to disable or disrupt this valuable and complex machinery are well within the reach of even technologically unsophisticated adversaries.

Indeed, with some U.S. military planners advocating the development of what would be the first-ever space-based systems for offensive operations—what the military refers to as force projection

—the country finds itself fast approaching a crossroads. Space, these planners assert, will usher in a revolution in global warfare, with U.S. space-based weapons delivering destructive force to any point on the globe within minutes, and without the risk or cost of sending troops.

Realizing the growing strategic value of space, in January 2001 a congressionally mandated space commission headed by incoming Secretary of Defense Donald H. Rumsfeld urged the United States to maintain the option of weaponizing space, identifying three potential missions for space weapons:

• Protecting existing U.S. systems in space.

• Denying the use of space and space assets to adversaries.

• Attacking from space a target anywhere on land, at sea, or in the air.

In the four years since the Rumsfeld commission released its conclusions, the report has continued to guide U.S. policymaking in this arena. For instance, the U.S. Air Force last year outlined a series of potential space weapons initiatives as part of its 176-page Transformation Flight Plan. Among the weapons described were space- and ground-based lasers, antisatellite missiles, and a futuristic constellation of orbiting high-power radio frequency transmitters capable of disrupting or disabling electronics. A press statement that accompanied the report's release in February 2004 described it as "a road map to the future."

The Idea Of Putting Weapons In Spaceis not new. Beginning in the 1960s, at a time when satellites were still quite rare, the former Soviet Union and the United States both tested antisatellite weapons. Despite several decades of development, however, neither country managed to deploy any such weapons. Then, during the Reagan administration, supporters of the Strategic Defense Initiative advanced proposals ranging from space-based lasers to "Brilliant Pebbles," numerous small orbiting projectiles to be fired at ballistic missiles in hopes of destroying them [see sidebar, "Missile Defense from Space"].