Trump in June ordered the creation of Space Force, which would become the sixth service in the US military, arguing the Pentagon needs it to tackle vulnerabilities in space and assert US dominance in orbit.

Currently, the Air Force oversees most space capabilities and there is some push back from officials who worry Space Force's mission would be duplicative and add bureaucratic bloat.

Defense Secretary Jim Mattis said this week that Pence is Trump's "point man" for Space Force, and Pentagon officials are working closely with his office.

Mattis last year voiced skepticism on the need to create a separate Space Force.

In a letter to a US congressman, he said he did "not wish to add a separate service that would likely present a narrower and even parochial approach to space operations," adding it would create extra bureaucracy and cost.

On Tuesday, however, the Pentagon chief said he fully supported the idea of creating a new command that would draw in members of existing military branches.

"We need to address space as a developing, war-fighting domain and a combatant command is certainly one thing that we can establish," he said.

The vast US military divides the globe into various commands, such as Central Command in the Middle East or Indo-Pacific Command in Asia, and so a new Space Command would be on an equal footing as these.

Though it would not be a full new branch of the military, it would still require a new headquarters and major organizational changes.

The Pentagon is set to release a report to Congress later Tuesday outlining steps towards meeting Trump's order. Only Congress can approve the creation of a new military branch.

Pence is due to deliver an address at around 11:15 am (1515 GMT).