Since Sputnik arced across the sky in 1957, space has essentially been a weapons-free zone - exempted from war at times by international treaties and at others by the prohibitive expense and impracticality of arming the heavens.
Today, however, as more nations gain access to space - and as success in war becomes far more dependent on satellite surveillance and communication - the United States is reassessing its space policy.
The new position, emerging in documents and congressional testimony, in many respects mirrors President Bush's military policy on the ground - expanding preemption and prevention into the ether, both to strike enemy lands and satellites during times of conflict and to keep America's satellites safe.
The president's vision could be scuttled by cost or controversy. Yet it marks a new moment in the debate over the appropriate use of space, as administration officials worry that one of America's greatest military advantages - dominance of space - could become increasingly vulnerable.
"The modern style of American warfare is impossible without [space]," says John Pike, a defense analyst at Globalsecurity.org. "It's one of the reasons that we're a superpower."
Never has that been more obvious than in Afghanistan and Iraq. While the first Gulf war offered glimpses into how satellites could support a superpower's efforts to wage war on the other side of the globe, the forces that entered Iraq in 1991 were different from those in Iraq today. Today's military is smaller, more agile, more technologically sophisticated - and more dependent on the space network.
"We're no longer talking about large, massed forces," says Maj. Gen. Michael Hamel, commander of Space Air Forces at Vandenberg Air Force Base in California. "With smaller forces, the way to [remain dominant] is through superior information, knowledge, and decisionmaking - and space becomes critical."
This is the military envisioned by Defense Secretary Donald Rumsfeld, and his vision goes even further - to a time when satellite technology helps connect soldiers to real-time data about the battlefield and commands a suite of robotic weapons.
"The lessons learned from Iraq and Afghanistan indicate technology has revolutionized the way we conduct military operations," said Rep. Terry Everett (R) of Alabama at a congressional hearing. "Space rests at the forefront of this revolution."
Yet this trend brings both benefits and concerns. On one hand, America enjoys virtually total control of space, giving it an advantage that no other nation can match. Yet as America's military might becomes increasingly reliant on satellite technology, it becomes more vulnerable if those satellites are destroyed.
For decades, the list of nations capable of sustained access to space other than the US began and ended with Russia. Yet other countries are gaining a toehold in orbit. The European Union, for one, is developing the first non-American network of global-positioning system (GPS) satellites - and has invited China to participate.
To administration officials, projects like the EU's Galileo not only herald a time when America could lose its intelligence hegemony in the heavens, but they also hint at a time when adversaries could have the technological know-how to target America's space assets. Rather than seeing this as inevitable, the administration has carved out an aggressive posture.
"Because we depend so heavily on space capabilities, we must be prepared when directed to confront adversaries on the high ground of space," acting Air Force Secretary Peter Teets told Congress last month. "If [diplomatic or nonlethal] measures fail, we reserve the right under international law to take defensive action against an adversary's space capability."
The Pentagon continues to develop its line of Experimental Small Satellites, which currently are intended to monitor malfunctioning satellites to determine whether they were victim to foul play.
Yet critics suggest that it is a small step from monitoring US satellites to attacking other satellites. To them, the administration is overreacting. China and Russia, they note, are pursuing new laws to outlaw weapons in space, and would be drawn into a space arms race only if the US went first.
"They will go there if we go there," says Theresa Hitchens of the Center for Defense Information here. "If somebody else did go first, we could go second very quickly and probably better."
Yet some analysts wonder if America is really all that close to preparing for space-based battle. After all, if such preparation were going to happen, it might have happened during the cold war, when the threat was clearer.
With other technologies like ground-based satellite jammers already in the US arsenal, they wonder if costly space-based antisatellite programs will ever take root.
"Space is a really good way to lose a lot of money," says Mr. Pike. In the future, he predicts, space "is going to look a lot like it does now."