The Pentagon is expected to send an interim report to Congress this week on how best to stand up the “Space Force” or some other kind of defense agency devoted to countering military threats in space.

The report, mandated by the 2018 National Defense Authorization Act, could play a big role in determining what the agency looks like, as President Donald Trump continues to urge a space force’s creation.

The question of whether the new space agency should be a separate military branch or just a sub-command is a hotly debated one in Washington.

Trump has called for the military to create a new branch equal to the Army, Navy, Air Force, Marine Corps, and Coast Guard, named “Space Force.”

“I’ve directed the Pentagon to begin the process of creating the sixth branch of our military. It’s called the Space Force,” he declared last week at the Veterans of Foreign Wars National Convention to applause.

Trump first declared his desire to stand up a space force in March. His administration has put an emphasis on improving the U.S.’s space capabilities. Last year, he launched by executive order the National Space Council, chaired by Vice President Mike Pence.

But while Trump can direct the Pentagon to begin planning for a space force, Congress would need to authorize the creation of a new branch, and fund it.

The idea of a space force equal to the other services has been received with much excitement in the Twitter-sphere and by several in Congress, but some experts and former officials are pouring cold water on it.

Deborah Lee James, former Air Force secretary under the Obama administration, argued at a Brookings Institution panel discussion on Monday that standing up a new service would cost money, time, and attention that would distract from improving the military’s ability to counter threats in space.

Standing up a service would entail designating uniforms, logos, service academies, and other things that would be disruptive to the mission, she said.

However, she said she would support a sub-unified combatant command like U.S. Strategic Forces Command that consists of its own sub-components depending on the specific task and service components from each military branch.

Brian Weeden, a former Air Force captain and technical adviser to the Secure World Foundation, agreed that standing up a separate service would be time-consuming and that there are other options, such as standing up a space corps related to the Air Force, like the Marines is to the Navy, or that would be like the Coast Guard for space.

Brookings Senior Fellow and Director of Research Michael O’Hanlon noted that the Air Force’s Space Command numbers about 40,000, which is roughly the same size as the Coast Guard.

Frank Rose, former assistant secretary of state for arms control, verification, and compliance under the Obama administration, said he was “undecided,” on whether a Space Force needed to be stood up.

“In reality, this is a very serious issue, and it is primarily driven by the development of anti-satellite capabilities by Russia, China, and others,” Rose said. “Is this the right way to deal with the ASAT threat? And that’s what really needs to be focused on.”

He said he would like to see more diplomacy on space, rather than just a military solution, and said the U.S. needed to engage Russia and China on space.

“I know it feels good to hit them,” he said, adding, “We also need to find a way to engage with them diplomatically.” He suggested restarting bilateral dialogues with them on space.

Steve Jacques, a retired Air Force officer and managing partner at Velos LLC, said he supported the idea of standing up Space Force, arguing that the U.S. military needed a “single belly button” to press on space issues.

“I think a focal point is needed,” he said. “We must have a focused, empowered person inside the national security establishment … we don’t have that, we simply do not have that. People have been preaching about this for a long time — it’s not there.”

However, he added that it could also be a corps or an agency and not necessarily a separate branch.

He said if the past 40 years showed anything, it was that the Pentagon was not able to deal with the increasing challenges in space.

“Something has to change,” he said. “A properly empowered, properly focused space force is the answer.”

He said other nations were becoming more militarized in space, and the U.S. risked falling behind. “Why are they gaining? Because they get it,” he said. “They understand it’s critical to their own national security.”

Rose agreed on needing leadership of the military space mission. “We’ve not had a legislated person in charge of space,” he said.

He said he hoped the debate over a space force would not become partisan and noted that Democrats in Congress like Rep. Jim Cooper (D-TN) also support the idea of a space force.

Rose commended the Trump White House for its focus on space.

“I actually think the Trump administration has done a good job,” he said. He noted the reestablishment of the National Space Council, how space is incorporated into the Nuclear Posture Review, and other national security strategies.

But, he reiterated, “We also need to talk to Russia and China.”