The US has adopted a tough new policy aimed at protecting its interests in space and denying "adversaries" access there for hostile purposes.
The document - signed by President Bush - also says "freedom of action in space is as important to the United States as air power and sea power".
The document rejects any proposals to ban space weapons.
But the White House has said the policy does not call for the development or deployment of weapons in space.
However, some military experts warn that by refusing to enter into negotiations on space weaponry, the US is likely to fuel international suspicions that it will develop such weapons.
The 10-page strategic document states that the US national security "is critically dependent upon space capabilities, and this dependence will grow".
"The United States will preserve its rights, capabilities, and freedom of action in space... and deny, if necessary, adversaries the use of space capabilities hostile to US national interests," it says.