President Donald Trump directed the Department of Defense and the Pentagon to establish a Space Force as the sixth branch of the Armed Forces in a meeting with the National Space Council today.

“We are going to have the Air Force and we’re going to have the Space Force, separate but equal. It is going to be something so important,” President Trump said. “Separate but equal” is an appalling turn of phrase given that it’s derived from Plessy v. Ferguson, the now-overturned Supreme Court precedent for segregation.

The announcement came as a surprise in a meeting where the newly revived National Space Council was set to unveil the first comprehensive policy on space traffic management. “The whole point of today’s meeting was not about this at all, it was about the space traffic management policy decision,” says Brian Weeden, director of program planning for the Secure World Foundation — an NGO that focuses on space policy.

Still, this isn’t the first time we’ve heard about Trump’s hopes for a Space Force; he first proposed the idea of a Space Force in March 2018 — contradicting Defense Secretary Jim Mattis’ opposition to creating a new military service. In a letter to the Committee on Armed Services, Mattis argued that it would just create more overhead and bureaucracy.

As it stands, the Air Force is largely in charge of controlling national security in space under the umbrella of the Air Force Space Command. Its responsibilities include supervising launches and controlling DoD satellites — including ones involved in missile early warnings, communication, and navigation.

“There’s a lot of complexity in making this change, since it involves creating a whole new Pentagon bureaucracy from scratch,” Weeden says. “Everything as mundane as new uniforms all the way through to new doctrine, and probably tens of thousands of new people ... it would be a really big change, and it’s not something to be taken lightly.”

Nevertheless, Trump doubled down on his Space Force hopes today. He framed US space exploration as “not just a matter of national identity, but a matter of national security,” he said. “So important for our military, so important, and people don’t talk about it.”

What he didn’t talk about today were details about what exactly the Space Force would do and how it would be funded. In fact, the president can’t just unilaterally create a new branch of the military in an off-the-cuff announcement, experts say.

The president told a US general to create a new Space Force as 6th branch of military today, which generals tell me they don’t want. Thankfully the president can’t do it without Congress because now is NOT the time to rip the Air Force apart. Too many important missions at stake. https://t.co/uYzqg1W8nE — Senator Bill Nelson (@SenBillNelson) June 18, 2018

“To actually create a space force, Congress would have to pass some legislation to do so — both to create it and to actually fund it,” Weeden says.

In fact, the National Defense Authorization Act for Fiscal Year 2018 already directed the DoD to prepare a report on establishing a “space corps,” according to Space News. The NDAA instructs the Deputy Secretary of Defense to hire an independent research organization without ties to the Air Force to “provide Congress with a roadmap to establish a separate military department responsible for national security space activities of the DoD.” That final report is due in August.

But plans for a Space Force may have been nipped in the bud more than fifty years ago by the Outer Space Treaty, which spells out what the treaty’s signatories are allowed to do in space. They’re not, for example, allowed to put nukes in orbit, on the Moon, or any other celestial body. The treaty also bans war games, military installations, or weapons testing sites there.

But that hasn’t stopped space from becoming weaponized: after all, satellites orbiting Earth are key for communication, military surveillance, and weapons guidance. Maybe creating a Space Force really is possible — but today’s announcement didn’t magically make it happen.

Update June 18th, 3PM ET: This story has been updated to include context for President Trump’s Space Force announcement today.

Update June 18th, 3:22PM ET: This story has been updated to explain the racist origins of the phrase “separate but equal.”