WASHINGTON – In 2005, Lt. Gen. Jim Mattis had advice on militarizing space for the future Defense secretary: be ready to rocket Marines around the globe to hot spots in two hours or less.

Now Defense secretary, Mattis has been charged by President Trump with creating a sixth armed service, the Space Force. Mattis can look to the advice from his younger self contained in documents he signed as commander of the Marine Corps’ Deputy Commandant for Combat Development.

It contained a wish list of capabilities the Marine Corps wanted for combat anywhere on the planet on short notice. The request to fund the Small Unit Transport and Insertion Capability, essentially rocketing a 13-man squad into action, is tucked into the document with more mundane, immediate concerns at the time, including protecting Marines from roadside bombs in Iraq.

The SUSTAIN request revived concepts that have rattled around the halls of the Pentagon in the decades since space travel and satellites became commonplace. Military planners have viewed the need to dominate space where, for instance, satellites, vulnerable to attack, guide everything from small units on the ground to precision guided bombs to their targets.

Trump echoed those concerns in calling for a separate military branch responsible for space.

"It is not enough to merely have an American presence in space, we must have American dominance in space," Trump said last month. "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 is a big statement.”

Mattis, however, initially resisted the idea of a separate service for space, writing to Congress last year that it would “likely present a narrower and even parochial approach to space operations.” Prominent military analysts like Michael O’Hanlon of the Brookings Institution have voiced similar concerns, arguing that the force would likely be derived largely from the Air Force, creating two weaker organizations.

By Aug. 1, the Pentagon will submit a plan to Congress on how it plans to organize its new approach to space. An interim report released in March noted that the U.S. military has held an advantage in space but rivals Russia and China are catching up. Dana White, the top Pentagon spokeswoman, has said the military understands Trump's guidance and will work with Congress to address them.

The new service would also require congressional action, and skeptics like Sen. Bill Nelson, the Florida Democrat on the Armed Services Committee, reside there. He tweeted last month that “now is NOT the time to rip the Air Force apart.”

"The Space Force concept is premature, and will probably disrupt progress the Pentagon has been making in space," said Loren Thompson, a defense and aviation analyst with the Washington-based Lexington Institute.

Nonetheless, Mattis and other senior officials have softened their opposition to Trump’s proposal, and the Pentagon is actively studying the possibility of creating a separate service.

Mattis, who had no immediate comment to USA TODAY about his earlier plans, could dust off the urgent need plea from the Marine Corps in 2002 that informed his 2005 recommendation for SUSTAIN, the acronym for the capability to "transport small, mission-tailored units through space from any point on the globe" within minutes of the order from the president.

The Marines have long sought to pioneer space fighting. In 1963, Marine Gen. Wallace Greene said space flight could have a "staggering" impact on projecting U.S. power. Greene, later the Marine Corps commandant, wanted Marines in space by 1968.

The Universal Need Statement envisioned a stealthy rocket ship that could loiter in low-earth orbit. "Needs to have the passenger cube capacity and on-board life support for a 13-person Marine infantry squad or task organized team(s)."

The concept would be to snuff out the spark of a threat before it blazed.

"Earliest intervention results in minimal force application, with consequent minimal visibility at the lowest national cost," according to the statement.

Critics, though, have noted that rocketing troops into space, landing them and extracting them would require enormous amounts of fuel and the lightest ship possible for efficiency. That would eliminate armor, leaving the ship vulnerable to attack. It's also unclear the tasks that 13 troops with small arms could accomplish or how they would leave the places they had rocketed into.

"There are no imperial battle cruisers in the Pentagon's space posture, just a collection of highly vulnerable satellites," Thompson said. "The Space Force proposal will get in the way of making them more resilient.

"The president's timing on proposing a Space Force is odd," he said. "The Air Force is devoting more of its money and intellectual capital to space today than ever before. It certainly isn't neglecting space."