Satellites orbiting high above Earth are a crucial resource for the U.S. military in terms of communications, reconnaissance and global positioning. But a new report warns that too much of a space military presence, mainly the use of space-based weapons systems, may inevitably cause more problems than they're meant to solve.

Should the U.S. military "weaponize" space, the report states, it will most likely be affect global commerce, weaken American ties with other nations and eventually lead to space weapons proliferation as other groups develop countermeasures or their own space weapons systems.

The study, called Space Assurance or Space Domination? The Case Against Weaponizing Space , was released by the Henry L. Stimson Center, a Washington D.C.-based nonprofit, nonpartisan think tank aimed at enhancing international peace and security.

"When you weaponize space, you invite company," said Michael Krepon, who wrote the report and served as the founding president of the Stimson Center. "When we go first, others will come second. That is an absolute certainty."

Once killer satellites start destroying one another above Earth, they will cause space debris that could harm benign satellites used by civilian agencies and companies around the world, which in turn affects global economy, according to the Stimson report.

If other nations or groups choose not to put their own space weapons in orbit, they could develop ground-based countermeasures like electronic jamming or spoofing devices to confuse U.S. machines. A ballistic missile could disable satellites in low-earth orbit by detonating a nuclear device, subjecting any ground troops relying intelligence from those satellites to possible attack, the study noted.

Finally, the report added, space weapons systems could hurt U.S. diplomatic ties on the ground, with other nations constantly mindful of its space forces in Earth orbit.

Krepon said there is a distinction between the current militarization of space -- which uses satellites to support forces on the ground -- and weaponization, defined in the study as the flight-testing and deployment of any system to specifically as systems used to "fight a war in space or from space, or military capabilities on the ground designed to kill satellites in space."

The U.S. military has had an established foothold in space for decades and its application in wartime was visually apparent during the recent war, and current occupation, in Iraq. Military forces there from the U.S. and other nations, rely heavily on satellites on everything from weather forecasts to signal detection and photointelligence.

Krepon said the United States Air Force (USAF), in particular, is creeping close to the threshold of space weaponization with its XSS satellite program. The XSS program, short for Experimental Satellite System, consists of a series of microsatellites smaller than 100 kilograms.

One such satellite, XSS-10, was successfully launched in 2003. Weighing about 62 pounds (28 kilograms), it demonstrated the ability to be activated soon after launch, maneuver close to its spent rocket and broadcast live video of the booster to officials on the ground. A follow-up mission, XSS-11, was set to conduct a similar mission -- but over a longer period of time -- sometime this year.

"But a maneuverable satellite like that could also be used to disable, stun, dazzle or destroy an object," Krepon told SPACE.com. Even if the U.S. military moves forward with a non-destructive system, one that disables enemy satellites rather than obliterating them, the foreign space forces that follow won't be so polite about the means they use to destroy spacecraft, he added.

The push to develop military systems in space in the current administration was boosted in 2001, when a government-assigned commission reported its findings on the United States' national security capabilities in space. Commissioners, then, reported a great need to protect American space systems, particularly since the government's growing dependence on satellites could make it an attractive target for enemies.

"Many foreign nations and non-state entities are pursuing space-related activities," reported the study, which was headed then by Donald H. Rumsfeld, who is now the Secretary of Defense. "If the U.S. is to avoid a 'Space Pearl Harbor' it needs to take seriously the possibility of an attack on U.S. space systems."

If space warfare becomes a reality, it should only be implemented as a last resort, according to the Stimson study.

"We are in a position to deter the first use of space warfare because of our predominant military power," Krepon said, adding that the U.S. is now in a position to cause grievous damage to any other state that engages in space warfare. "The prospect of deterrence can be quite meaningful in space."