President Donald Trump has directed the Pentagon to create a "space force" as a new, sixth military branch to oversee missions and operations in the space domain.

"We must have American dominance in space," Trump said during a speech at the National Space Council meeting, held at the White House on Monday. "I'm hereby directing the Department of Defense to immediately begin the process to establish a space force as the sixth branch of the armed forces."

"We are going to have the Air Force, and we are going to have the space force," Trump said. "Separate, but equal. It is going to be something so important."

Trump then directed Gen. Joseph Dunford, the chairman of the Joint Chiefs, to "carry that assignment out."

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"Let's go get it, General," he added to Dunford, who was at the council meeting.

The Air Force did not immediately have a statement in response to the announcement, and directed all questions to the office of the secretary of defense.

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In March, Trump first revealed he had an idea for a "space force," or separate military service for space.

The Pentagon, meanwhile, has been in a months-long debate over an additional branch.

Trump shared his vision for the force during a visit to troops at Marine Corps Air Station Miramar, California.

"Because we're doing a tremendous amount of work in space, maybe we need a new force," he said. "We'll call it the space force."

Trump's comments came a few months after discussions had wound down in the Pentagon about a separate military force for space.

Lawmakers have pushed the Air Force to stand up a branch for space within the service in hopes of taking adversarial threats in space more seriously.

Both Air Force Secretary Heather Wilson and Chief of Staff Gen. David Goldfein have been trying to discourage talk of a separate military branch, maintaining that the Air Force has the means and the personnel to meet current requirements for space.

"This [Air Force] budget accelerates our efforts to deter, defend and protect our ability to operate and win in space," Wilson told a House Appropriations Committee panel days after Trump's first announcement. "There are a number of different elements of this with respect to the space -- the space portfolio."

Goldfein agreed with the secretary during the March hearing, and added there is no question space is a warfighting domain in need of better protection. The Air Force has overseen the domain since the mid-1950s.

"As a joint chief, I see that same responsibility as the lead joint chief for space operations is making sure that we have those capabilities that the joint team requires. And so, as the president stated openly, this is a warfighting domain," Goldfein said. "That is where we've been focused. And so I'm really looking forward to the conversation."

Last year, Rep. Mike Rogers, R-Alabama, and Rep. William "Mac" Thornberry, R-Texas, first created language in the fiscal 2018 National Defense Authorization Act which would have required the service to stand up a "U.S. Space Corps."

Soon after, Goldfein, Wilson and even Defense Secretary Jim Mattis publicly downplayed the idea, citing costliness and organizational challenges.

And while lawmakers ultimately removed language requiring such an overhaul of the Air Force's mission, they still required a study of a space force and also backed changes to the management of the space cadre.

Rogers and other key lawmakers believe it is still possible to stand up a "space corps" within three to five years, and have still chastised the Air Force for not creating something like it "yesterday."

"The situation we are in as a nation, the vulnerabilities we have to China and Russia, I'd like for the American public to know more, [but] I can't because I don't want to go to jail for leaking classified info. But we're in a really bad situation," Rogers said at a Center for Strategic and International Studies event in March.

Rogers has looked to Trump for support on the new space mission.

"Looking forward to working with @realDonaldTrump on this initiative!" he tweeted March 14.

-- Oriana Pawlyk can be reached at oriana.pawlyk@military.com. Follow her on Twitter at @oriana0214.