US: President George Bush has adopted a new national space policy that asserts the United States' right to prevent adversaries from using space for hostile purposes.
The new policy, which is the first major revision of US space policy in 10 years, opposes any international treaties that would limit US access to or use of space.
Published quietly a month ago, the new policy puts a greater emphasis on the defence dimension of space but it does not envisage the development of weapons systems in space.
"The United States considers space capabilities - including the ground and space segments and supporting links - vital to its national interests," it says.
"Consistent with this policy, the United States will: preserve its rights, capabilities, and freedom of action in space; dissuade or deter others from either impeding those rights or developing capabilities intended to do so; take those actions necessary to protect its space capabilities; respond to interference; and deny, if necessary, adversaries the use of space capabilities hostile to US national interests."
The policy says that space systems should have rights of passage without interference, and that the US would interpret any interference with its systems as an infringement on its rights.
"Freedom of action in space is as important to the United States as air power and sea power," states the policy.
"In order to increase knowledge, discovery, economic prosperity, and to enhance the national security, the United States must have robust, effective, and efficient space capabilities."
The last time the US national space policy was revised, under the Clinton administration in 1996, the emphasis was on education and scientific discovery.
The new policy puts defence at the heart of US interests in space and makes clear that Washington believes that no new arms control agreements are needed because there is no arms race in space.
Two years ago, the US air force published a "Counterspace Operations Doctrine" that called for a more active military posture in space and said that protecting US satellites and spacecraft may require "deception, disruption, denial, degradation and destruction".
The new policy calls on the Pentagon to provide space capabilities for missile-warning systems and "multi-layered and integrated missile defenses".
Some countries want to ban space weapons but the US has always opposed that idea, voting at the UN last year against a call for negotiations on a weapons ban that was backed by 160 countries.