NATO Secretary General Jens Stoltenberg insisted space was purely defensive and did not include plans to put weapons into orbit. But it represented a marked departure from the United States, which is preparing to fight a future war in space if necessary.

Details about the administration's Missile Defence Review - the first compiled since 2010 - are expected to be released during President Donald Trump's visit to the Pentagon.

"Thinking about space as a separate entity in itself that deserves attention and expertise, I think is a good idea," said Matthew Overton, executive director of the Conference of Defence Associations Institute.

The U.S. Department of Defense says the development of anti-satellite laser weapons by China and Russia is among the key concerns necessitating the need for a U.S. Space Force.