Washington (AFP) - President Donald Trump said Tuesday he wants the US military to create a new "space force," adding to the Pentagon's current ground, navy and air forces.

Trump told troops at the Miramar Marine Corps Air Station near San Diego that the new group would be able to encapsulate the "tremendous amount" of work the military and government are doing in space-related defense.

"My new national strategy for space recognizes that space is a war-fighting domain, just like the land, air and sea," Trump said.

"We may even have a space force... We have the air force, we'll have the space force, we'll have the army, the navy.

"Maybe we'll have to do that. That could happen," he said.

Since taking office, Trump has frequently touted his support for the US military and placed high-ranking generals in top White House and cabinet posts.

Last year some legislators pushed a bill in Congress that included a provision to establish a new branch of the military dubbed the Space Corps.

But the military itself has resisted, saying it does not need to create another force and its attendant bureaucracy.

"At a time when we are trying to integrate the department's joint warfighting functions, I do not wish to add a separate service that would likely present a narrower and even parochial approach to space operations," Defense Secretary Jim Mattis told Congressman Michael Turner in a letter last July.

It would be "premature to add additional organizational and administrative tail to the department at a time I am trying to reduce overhead," he added.

The idea was finally dropped from the Pentagon's funding bill by the end of last year, but it retains some support in Congress, where advocates say the US is facing significant strategic vulnerabilities in the face of Russian and Chinese pushes into space warfare.

Republican Representative Mike Rogers told a February 28 conference at the Center for Strategic and International Studies that a separate space corps could be carved out from the air force within "three to five years".

He said China and Russia have become "near peers" to the US in space capabilities, and the US is not pushing hard enough to stay ahead.

"That's unacceptable that we have allowed that to happen, particularly in a day and age when it is essential to have those space capabilities to fight and win wars," he said.