President Trump is directing the Pentagon to immediately begin the process of creating a new Space Force military service, a major move that would wrest control of military space from the Air Force and intensifying a debate between the military and Congress over whether the move is necessary.

“When it comes to defending America, it is not enough to merely have an American presence in space. We must have American dominance in space. So important. Very importantly, I’m hereby directing the Department of Defense and Pentagon to immediately begin the process necessary to establish a Space Force as the sixth branch of the armed forces. That’s a big statement,” Trump said a meeting of the National Space Council at the White House on Monday. “We are going to have the Air Force and we are going to have the Space Force, separate but equal.”

The announcement comes as the Pentagon is still working to finish up studies on military operations in space, including an independent review ordered by Congress on how it would create a new service focused on protecting the U.S. against growing space threats from countries such as China and Russia. The review is not slated to be turned over to lawmakers until December.

Defense Secretary Jim Mattis recently said it would be premature to create the new service without completing the review and fully understanding the issues facing the military in space. Last year, Mattis took the unusual step of writing a letter of opposition to lawmakers who were considering an initiative to create a Space Force.

“I oppose creation of a new military service and additional organizational layers at a time when we are focused on reducing overhead and integrating joint warfighting functions,” Mattis wrote in the Oct. 17 letter to Republican and Democrat leaders on the House and Senate Armed Services committees.

So far, the Pentagon has no response to the president’s signed directive, which personally and publicly ordered Joint Chiefs Chairman Gen. Joseph Dunford to it carry out .

“Gen. Dunford, if you would carry that assignment out, I would be very greatly honored,” Trump said the Space Council meeting at which Dunford was present.

The Air Force, which handles about 80 percent of the military's space operations, strongly opposed the idea of a Space Force when it was introduced by House lawmakers last year, saying it would merely add unneeded bureaucracy. Since Trump came out in favor of the idea earlier this year, service leaders have said they are open to new ideas on how to handle space.

The Air Force referred all requests for comment to the Defense Department.

Some members of the House Armed Services Committee have been pushing for the past year for a Space Force. Reps. Mike Rogers, R-Ala., and Jim Cooper, D-Tenn., have argued that the Air Force is botching its security job in space and the only way to get ahead of the growing threats is to create a new service to handle the operations within the Department of the Air Force.

“I am thrilled to have President Trump's continued support for this critical mission to help strengthen our national security. I look forward to working with the President to make this initiative a reality," Rogers said.

A spokesman for Democrats on the House Armed Services Committee said the minority had no heads up that Trump was going to make an announcement ordering the new military service.

Jamie J. McIntyre contributed to this report.