US President Donald Trump said that he would direct the Defence Department and the Pentagon to create a new "Space Force" - an independent sixth branch of the armed forces.
Trump has floated this idea before - in March, he said he initially conceived it as a joke - but has offered few details about how the Space Force would operate.
Trump said that the branch would be "separate but equal" from the Air Force. Joseph Dunford, chairman of the Joint Chiefs of Staff, would oversee its creation.
Saying that he does not want "China and other countries leading us," Trump said space was a national security issue.
The Outer Space Treaty, which the United States signed in 1967, bars states from testing weapons and establishing military bases on the moon and other celestial bodies.
It also prohibits the placement of weapons of mass destruction in orbit around Earth. But the treaty has no enforcement mechanism (indeed, the Air Force's unmanned space plane, the X-37B, has completed several clandestine missions).
Trump has floated creating a Space Force for months, but the idea goes back at least a year to a proposal by congressmen Mike Rogers, (R), and Jim Cooper, (D).
Rogers, chairman of the House Armed Services strategic forces subcommittee, and Cooper, the ranking Democrat on the subcommittee, argued that it made sense to have a "Space Corps," a separate branch of service with its own four-star general serving on the Joint Chiefs of Staff. Under their plan, it would have reported to the Department of the Air Force, in similar fashion to how the Marine Corps reports to the Department of the Navy.
Last northern autumn, that proposal was scrapped amid resistance from senior Pentagon officials, including Defence Secretary Jim Mattis, Air Force Secretary Heather Wilson and Air Force Chief of Staff General David Goldfein, who said it would create unnecessary costs and bureaucracy.
"I oppose the creation of a new military service and additional organisational layers at a time when we are focused on reducing overhead and integrating joint warfighting functions," Mattis said in October in a memo to Senator John McCain, chairman of the Senate Armed Services Committee.
Some are worried that the Space Force would duplicate existing efforts. The Air Force already maintains a Space Command, for example.
Retired Air Force Lieutenant General Dave Deptula, dean of the Air Force Association-founded Mitchell Institute for Aerospace Studies, described the decision to create a Space Force as "another example of ready, fire, aim".
The announcement was made at a meeting of the National Space Council, at which Trump signed a new space policy directive aimed at reducing debris in Earth's orbit. The policy sets up new guidelines for satellite design and operation, as well as tracking the growing amount of clutter in space.
But, citing the number of regulations his administration has dismantled since he took office, Trump warned the space council, "Don't get too carried away."
The President also reasserted plans to land astronauts on the moon again and, eventually, Mars. But his administration has provided few specifics about the architecture of its moon programme or a timeline for returning to the lunar surface.