It wasn't clear if the Cosmos satellites could attack U.S.-245, an American surveillance spacecraft.

"It has the potential to create a dangerous situation in space," said General Jay Raymond, head of the Pentagon's Space Command.

The incident passed, but it marked a new stage in the mounting arms race in space, where potentially bomb-armed satellites, laser-shooting spacecraft and other technologies have moved from science fiction to reality.

The stakes were made clear Monday when Russia launched a missile from Earth and blasted to pieces one of its satellites in a show of force.

NATO Secretary General Jens Stoltenberg called the act "reckless."

"It demonstrates that Russia is now developing new weapons systems that can shoot down satellites," he said at a meeting Tuesday with EU defense ministers.

Kamikaze satellites

The militarization of space is as old as the space race itself—as soon as Sputnik was launched into orbit in 1957, Washington and Moscow began exploring ways to both arm and destroy satellites.

In the beginning, the biggest worry was nuclear weapons in space. In 1967 the superpowers and other countries signed the Outer Space Treaty, banning weapons of mass destruction in orbit.