“Space—the final frontier.”

For fans of Star Trek, the phrase evokes the epic mission of a fictional starship, bound for adventure beyond the stars, “to boldly go where no man has gone before.” For President Donald Trump, humankind’s mission to the final frontier has a very different goal.

On Monday—perhaps in a bid to distract from an appalling humanitarian crisis brewing on the nation’s southern border—President Trump pointed the nation’s eyes towards the heavens with an unexpected announcement that he was directing the Pentagon to establish a “Space Force” as the sixth branch of the U.S. Armed Forces.

“When it comes to defending America, it is not enough merely to have an American presence in space—we must have American dominance in space,” Trump said at a White House meeting of the National Space Council. “Very importantly, I am 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.”

President Trump further pledged that the Air Force and the “Space Force” would be “separate but equal” branches of the military, before telling Marine General Joseph Dunford, the chairman of the Joint Chiefs of Staff, to “go get it.”

“Remember: economically, militarily, scientifically, in every way, there’s no place like space,” Trump said. “Good luck, Gen. Dunford and the Joint Chiefs—I want to wish you a lot of luck with Space Force.”

But experts in space law told The Daily Beast that the president’s eagerness to add a new, space-based service to the military might be grounded by decades of international law —and could be disastrous for the U.S. in the long run.

“The Outer Space Treaty does allow the presence of the military in space—they have been in space since the beginning—but they are restricted in what they can do,” Professor Joanne Gabrynowicz, Director Emerita of the National Center for Remote Sensing, Air, and Space Law at the University of Mississippi School of Law, told The Daily Beast. “For example, they could not do anything with nuclear weapons or weapons of mass destruction—those are strictly prohibited in space.”

The Outer Space Treaty of 1967, of which the U.S. is both a signatory and ratifier, prevents any nation from declaring sovereignty over space or heavenly bodies, and prohibits space-faring countries from blocking other nations from exploring space. There are further restrictions over military presence on heavenly bodies like the Moon, which according to the treaty “shall be used exclusively for peaceful purposes.”

Gabrynowicz, a director of the International Institute of Space Law and an official observer to the the legal subcommittee United Nations Committee on the Peaceful Uses of Outer Space, noted that because space is a global commons—“like the high seas or Antarctica”—the full force of terrestrial law would also apply to any militarized space force.

“There’s a whole body of international law that would apply, in addition to space law,” Gabrynowicz said. “The concept of the use of force is a very rich and deep concept in international law that has a lot of development, and all of that would be applicable as well.”

Those legal restrictions would severely hamper Trump’s more gung-ho visions of an operative “Space Force,” but the president’s primary obstacle to its creation may be more terrestrial. The five extant branches of the U.S. military have long opposed the formation of another branch —the first since the formation of the Air Force more than seven decades ago— space-based or otherwise.

In a July letter addressed to a member of Congress, for example, Secretary of Defense Gen. James Mattis said that he was opposed to creating a new military branch in space, which “at a time when we are trying to integrate the Department's joint warfighting functions... would likely present a narrower and even parochial approach to space operations versus an integrated one we’re constructing under our current approach.”

Secretary of the Air Force Heather Wilson echoed Mattis’ fear of bureaucratic buildup. “The Pentagon is complicated enough. This will make it more complex, add more boxes to the organization chart and cost more money,” Wilson told CNN at the time. “If I had more money, I would put it into lethality, not bureaucracy.”

Military hostility to the creation of a “Space Force” may be due in large part to concerns that the new branch’s budget would come out of their own pockets. Current allocations for the Air Force’s space procurement appropriations represent a huge portion of the branch’s overall budget—satellites are pretty expensive, after all—which might explain the Pentagon’s plainly unenthusiastic response to President Trump’s directive.

“We understand the president’s guidance,” said chief Pentagon spokesperson Dana White, in a statement provided to The Daily Beast. “Our Policy Board will begin working on this issue, which has implications for intelligence operations for the Air Force, Army, Marines and Navy. Working with Congress, this will be a deliberate process with a great deal of input from multiple stakeholders.”

When asked how funding for a “Space Force” might impact other branches, the White House was almost as noncommittal as the Pentagon.

“The president’s National Strategy for Space calls for American leadership, preeminence, and freedom of action in space, and he sees a separate service focused on space as a critical piece of that end state,” deputy White House press secretary Raj Shah said in a statement to The Daily Beast. “The National Space Council and other White House offices will work closely with the Department of Defense on successful implementation of the President’s direction.”

Even if President Trump succeeds in persuading career members of the military that his proposed “Space Force” is vital to national security, the idea of a “Space Force” as a Starship Troopers-esque military branch of armed astronauts waging war in zero gravity is farcical, Gabrynowicz said.

“If there were a war in space, the United States is the country that has the most to lose,” Gabrynowicz said. “We have more important assets in space than any other nation—we have communications satellites, remote sensing satellites, we have all sorts of stuff up there, weather satellites, things that observe the earth. Every communication on Earth, most of it goes through a satellite, somehow. When you think of how much stuff there is in space, fighting a war there puts all of those assets at risk.”

Conflict in space could even put human activity in space itself at risk.

“One of the really serious issues in space is orbital debris,” Gabrynowicz said. “If you’re going to start doing military activities in space that cause assets to break up or be destroyed, you’re risking a substantial addition to the debris problem.”

Such a debris field, the so-called Kessler syndrome made famous in the 2013 film Gravity, could cause a runaway series of collisions between satellites in low-earth orbit. The ensuing debris cascade could effectively destroy global communications satellite capabilities for decades.

President Trump may not be aware of such concerns. In March, when he first floated the concept of a “Space Force” during a speech in front of service members at Marine Corps Air Station Miramar in San Diego, President Trump declared that “ space is a war-fighting domain, just like the land, air, and sea.”

But the Trump Administration’s plans to add “breaking space law” to its long list of shattered norms may run into an even more mundane barrier than Pentagon reticence: congressional inaction. Congress would need to approve the creation of any “Space Force,” and at least one of Capitol Hill’s major advocates of space exploration is in no rush.

“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,” tweeted Florida Sen. Bill Nelson, (D-Fla.), who once served as a payload specialist on the Space Shuttle Columbia.

“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.”