How the military views outer space and cyberspace as battlefronts in future wars are likely topics in the administration's new national defense strategy.

WASHINGTON — Space and cyber warfare moved up the national security priority list during the Obama administration, and are expected to rank even higher under the Trump presidency.

Details on how the military views outer space and cyberspace as battlefronts in future wars should emerge in the national defense strategy that Defense Secretary Jim Mattis is expected to unveil Friday.

The national defense strategy — a forward-looking take on the challenges facing the U.S. military and how it is posturing itself to tackle those threats — is what used to be known as the QDR, or Quadrennial Defense Review. Congress last year determined that the QDR had no real value and asked the Pentagon to provide instead a more candid picture of its global commitments and requirements. The thinking is that lawmakers need to better understand what resources are needed for the military to fulfill those responsibilities.

Andrew Philip Hunter, director of the Defense-Industrial Initiatives Group at the Center for Strategic and International Studies, said space and cyber are likely to feature prominently in Secretary Mattis’ first national defense strategy.

In the first year of the Trump administration, space, cyber and missile defense have “really risen on the scope as modernization priorities,” Hunter said Wednesday at a CSIS news conference. Although it is still not clear that the rhetoric about the importance of space and cyber will be matched by policy and funding.

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Space and cyber are “new investment categories that are trying to displace, to some extent, existing force structure,” he said. Defense leaders and strategists have said the military needs to invest in modern technology to improve data analysis, intelligence, surveillance and other information-centric capabilities. But most of the Pentagon’s budget today is spent on old-school weapons. This creates a dilemma for the administration as it tries to position the military to win in the so-called “great power competition” against Russia and China.

“In order to dramatically increase investment in space, the Air Force will probably be required to reduce the size of its tactical fighter fleet in order to be able to afford that kind of investment,” Hunter said. “All of the services are being forced to reallocate force structure into the cyber mission in a pretty major way. That’s hard to do.”

Shifting resources away from traditional military systems to emerging areas of warfare like space and cyber will require some heavy political muscle, Hunter said. “That means it has to come from the secretary,” he added. “Left to their own devices, it’s very hard for the services to make that tradeoff. And that’s why, if it’s not articulated in the strategy, if it’s not coming from the secretary, it’s probably not going to happen.”

The new strategy also may begin to answer questions that the space and arms-control communities have been asking for a long time, such as how the military plans to deter attacks as space becomes more militarized,

That is the “big, burning issue that has not been resolved,” said Todd Harrison, director of the Aerospace Security Project and senior fellow at CSIS.

“What are we going to do in space to reestablish or improve a stable deterrent posture?” Harrison asked. “We do not want to fight a war in space. That’s a war that’s not going to go well for anyone,” he insisted. “If you know anything about orbital mechanics and orbital debris, we don’t want it to go there.” Military leaders have made this point as well.

How the Pentagon would deter future enemies from launching attacks in space in unclear, said Harrison. “And we’re at a point now where deterrence is not as clear that it will work in space,” he said. “We’re worried about that. The Department of Defense is worried about that.” He wonders whether this strategy will help reestablish a stable “deterrence posture” in space.

In a leaked draft copy of the soon-to-be-released Nuclear Posture Review, the administration highlights the risks that, if a nuclear crisis erupted, U.S. adversaries would immediately target key strategic space assets such as missile-warning and command-and-control satellites.

“In the nuclear realm, it’s long been understood that if you’re actually getting into a nuclear conflict, that of course both sides are going to try to take out the space assets of the other,” Harrison said. “If you’re at that point, the gloves are off.”

That concern is not new, he noted. But deterrence in space has become more challenging for the United States because the same satellites are used for strategic and tactical missions. Classified communications and intelligence gathering satellites that were created to support a nuclear war routinely are employed in conventional missions.

What the Trump administration has to address, Harrison said, is “how do we architect these systems to do what we need them to do in a nuclear crisis, but also to be resilient to attack in a nonnuclear crisis?”

During the Cold War, only the Soviets posed a credible threat to U.S. space systems. “And we basically had an understanding between the two countries: ‘If you attack our space systems, we’re going to regard that as a prelude of a full-scale nuclear war.” The world today is different, and the U.S. military has become hugely dependent on space, even for low-intensity counterinsurgency operations.

“So why wouldn’t an adversary, even a non-state actor, try to disrupt these systems?” Harrison asked. “And we’ve seen evidence of that, things like jamming our satellite-communications signals in Iraq and Afghanistan,” he said. “It is a much more complicated deterrence problem that we have today. We can’t simply assume that the threat of nuclear retaliation is going to deter someone from interfering with our space systems.”

Deterrence is even more difficult as anonymous cyber attacks can disrupt satellites signals. “You can’t prove it,” said Harrison. “There’s not something blowing up. It’s photons interfering with one another,” he said. “Can we really deter those types of attacks anymore?” And when deterrence fails, “we need architectures in space that can withstand attacks, that are resilient.” Further, “we need a posture that makes us more credible that we can deter these types of actions.”