On March 7, 2023, The National Interest published this occasional paper in “Pyongyang Goes Nuclear—This Time in Space.” Click here to read the full article.

Last week, South Korean President Yoon Suk Yeol catalyzed a once forbidden public debate over whether or not South Korea should go nuclear by suggesting that Seoul might need to acquire its own nuclear arms if security tensions with North Korea worsen. This prompted a flurry of press coverage on what Washington was prepared to do to use its nuclear forces to fortify South Korea’s security against any North Korean land attack.

In all of this, there was no mention of North Korea possibly using its nuclear weapons to disable the world’s growing number of dual-use, low-Earth orbit satellites, such as Starlink.

As the attached after-action report on NPEC’s latest war game, “North Korea Goes Nuclear in Space,” makes clear, this possibility cannot be dismissed. First, North Korea and China both have an interest in disabling such satellites as they can afford U.S. and allied military forces secure communications and information needed to target Chinese and North Korean military units. The Chinese have been quite vocal about this.

Second, because neither China nor North Korea have ratified the Limited Test Ban Treaty and because the Outer Space Treaty only clearly bans orbiting nuclear weapons in space, a sub-orbital, low-Earth detonation of a nuclear device, they may view such attacks as being legal.

Finally, the effects of such an attack against low-Earth orbit satellite constellations, including some of America’s most important military systems, would be devastating. The Chinese know this as the People’s Liberation Army’s Northwest Institute of Nuclear Technology publicly announced it has modeled such an attack with what it claims was a startling success.

How might such an attack be mounted? What might its military implications be? How might the United States and its allies best deter such an attack or cope with one after it was made?

NPEC wanted to find out. It tapped some of the nation’s leading space, nuclear, and military experts and designed and executed a sophisticated three-move war simulation this summer.

Attached are the key findings and a link to the after-action game report. The most important takeaway is that the United States and its key space-faring allies need to take the nuclear space threat more seriously by preparing a set of satellite hardening, space constellation reconstitution, and space system resiliency plans to mitigate and deter such attacks.

 

Pyongyang Goes Nuclear in Space: An After-Action Report

 

Wargame Scenario and Rationale:

In the early 2000s, many hoped states might rely less on nuclear weapons for their security. Today, that hope seems remote. China is dramatically increasing the size and quality of its nuclear arsenal. Russia is developing new nuclear weapons. North Korea is accelerating its long-range nuclear strike programs and India’s and Pakistan’s nuclear arsenals continue to grow. Depending on what occurs in Ukraine and Iran, more nations may acquire nuclear weapons options of their own.

Parallel to these developments, the military salience of space has increased dramatically. Not just the United States and Russia, but China, Europe, Japan, the Koreas, Israel, and India have begun to develop military space capabilities. Just as many states are planning missions to the Moon. Finally, the development of dual-use commercial space systems that can be used for military purposes is expanding significantly.

The space wargame described below focuses on the collision of these two trends by simulating North Korea’s use of nuclear weapons in space. Initially, some of the game’s participants thought this was quite unlikely; mid-way through the game, though, they warmed to the idea. Some suggested that China might exercise the option.

They were prescient. Twelve weeks after NPEC completed its simulation, The South China Morning Post reported the People’s Liberation Army’s Northwest Institute of Nuclear Technology had simulated a nuclear weapons strike designed to knockout dual-use satellite constellations, such as Starlink. The stated aim of the computer-simulated attack was to prevent Taiwan from exploiting such militarily useful commercial systems. The article noted that the Limited Test Ban Treaty prohibits the detonation of nuclear weapons in space and the atmosphere. It failed, however, to point out that neither China nor North Korea is parties to the treaty.

The game scenario, in short, is plausible. By the end of the decade (when this simulation’s war takes place), tens of thousands of small, commercial, networked satellite systems will be flying in low-Earth orbit. These satellites will complement the U.S. Defense Department’s own space architecture, which includes national security systems flying in low, medium, and geosynchronous orbits. Hostile states will want to threaten them.

What’s the worst they might do? This report gives an extreme answer. Some might ask why consider it. The answer is simple: U.S. national policies frequently focus on dire hypotheticals — e.g., massive nuclear wars, global warming catastrophes, pandemics, etc. — to shape plans not only to hedge against the worst, but to deal with lesser, included threats. U.S. space policy arguably doesn’t yet have such an organizing worry. The scenario this report focuses on might help.

The war described in the report begins in the spring of 2029. The DPRK tests an ICBM that inadvertently travels further than intended, triggering U.S. missile defenses. No interception is made, but the U.S. demands North Korea show a good-faith effort to avoid further provocations by garrisoning its mobile missile force and by beginning U.S. reconnaissance flights near North Korea. Washington subsequently increases pressure on North Korea to accede to these demands by asking the United Nations to approve a selective blockade of North Korea and placing U.S. strategic forces on alert.

North Korea refuses America’s demands, begins a general mobilization, and warns Washington that if the United States fails to end its nuclear alert and refuses to schedule the removal of its troops from the South, war will ensue. Tensions continue to build. Then early in June, North Korea launches a satellite into orbit and warns of a possible nuclear explosion in space unless the U.S. and ROK stand down. Washington contacts Beijing in hopes of getting China to pressure the North Koreans to relent. Chinese officials counsel Washington to negotiate with Pyongyang directly, noting that North Korea has not yet violated any treaty. The United States goes to the United Nations Security Council with a sanctions resolution against Pyongyang’s space provocation. Russia and China block its approval.

Throughout this crisis, U.S. officials try to determine if North Korea’s satellite is actually carrying a nuclear payload but are unable to do so. In mid-June, North Korea launches another payload into space, this time over the North Pacific. Well before entering full orbit (which, if it did, would constitute a clear violation of the Outer Space Treaty), the payload detonates, releasing 10-20 kilotons of nuclear energy into low-Earth orbit. All satellites in line of sight of the explosion are immediately disabled. U.S. space experts predict that the rest of the world’s satellites in lower low-Earth orbit will be disabled in a matter of days to several weeks. Tactical military communications and reconnaissance in Korea are hampered by North Korea’s low-Earth orbit attack. Shortly after the detonation, North Korea invades South Korea.

 

Key Takeaways:

At each move, the game focused on what the United States and its closest space-faring allies would do to deal with each of these crises. This produced four takeaways:

1. The popular notions that space warfare will stay in space and that international limits can prevent hostile actions from occurring there are both strong and wrong. Diplomats hope that with enough rules of the road, norms, and diplomatic signaling, the worst in space — military combat — can be avoided. Yet, the strong belief that diplomatic limits might prevent hostile military actions in space is betrayed by deep ambiguities in the space restrictions we have. In this regard, the U.S. team insisted North Korea’s nuclear detonation violated the Outer Space Treaty. China, however, disagreed and the U.S. Department of Defense legal experts agreed with China: Unless it can be proven that a nuclear device detonated while it was clearly in orbit or “on station,” there may be no foul. Indeed, under the Outer Space Treaty, both the Chinese and Pentagon lawyers insisted that a state can legally inject a nuclear weapon into space with a missile and detonate it so long as the warhead does not fly at least one, complete Earth orbit. Of course, exploding a nuclear weapon in the atmosphere would violate the Limited Test Ban Treaty but it is legally unclear how far out the atmosphere extends. More important, North Korea never signed the treaty. Also,  there is nearly no easy way to verify if an orbiting spacecraft is carrying a nuclear warhead. This makes enforcing the Outer Space Treaty’s ban on “stationing” or detonating nuclear weapons in space all but impossible until the treaty itself is violated with a detonation. This suggests the diplomatic utility of clarifying what disagreements we are likely to have with hostile states on these matters even if agreement on preventing a nuclear explosion in space is not immediately possible. For decades, the United States and its allies have sought to establish clear rules whose violation has consequences. Although desirable, this is still all too aspirational. NPEC’s previous China space game struggled with the lack of clear rules to limit dangerous space proximity operations as well and concluded that only rules that could be self-enforced would likely be of any utility. Unfortunately, nothing in this Korean game suggested otherwise. As for the plausible hawkish hope that with enough investments in military space capabilities, nuclear attacks in space can be deterred or, at least, be prevented from leading to conflict on Earth, the game provided no clear proof. What the game did confirm, however, is the military imperative to develop space and other command, control, communications, surveillance, and intelligence systems that can survive such attacks.
2. Developing satellite hardening and constellation reconstitution options to respond to a nuclear detonation in space are obvious hedges; far less obvious is what should be done to secure such options. All of the game’s players agreed that after a high-altitude nuclear explosion, there would likely be a race to reconstitute one’s satellite constellations. There also was significant agreement about what should be reconstituted — satellites and launchers — and how — by stockpiling certain materials, satellites, launchers, and other items, as well as ramping up manufacturing and mobilization base, etc. There was far less agreement or consideration, however, about when to reconstitute — early, when satellite lifetimes would be limited, or later, after the radiation levels in the Van Allen Belts had declined, allowing newly inserted satellites to survive longer. Nor was there agreement about where to focus the reconstitution efforts — in upper low-Earth orbit, medium-Earth orbit, in geosynchronous-Earth orbit, or on alternative, non-space-based, terrestrial systems. It also was unclear who might win in such a reconstitution race – China or the United States – and why. Some believed that the United States and its allies had a launch and satellite infrastructure and technology lead as well as a larger mobilization base than China. Others believed China would steal a march on any reconstitution race given its much quicker acquisition times. The game also stumbled across another reconstitution problem. Most players supposed that the Russian Soyuz capsule would be available on the U.S. space station in 2029. It might not. Developing U.S. or allied escape capsules would be desirable for both government and commercial space stations and operations on the moon. Finally, there was disagreement about how much hardening should be required. Some said it was pointless to demand this of commercial space firms, that if the U.S. government did, these firms would simply go overseas. Others said hardening should be proportionate to the risk being run (is the satellite in low-Earth orbit, near debris, able to cope with strong solar storms, radiation, etc.). Others insisted that if the commercial satellite provided government services, their government contracts could be conditioned upon meeting certain hardening requirements. Yet others said the government should help pay for such hardening. Some took the position that low-Earth orbit satellites ultimately were not that important to U.S. and allied security and prosperity. Others disagreed. What is clear is the need for our government to resolve these disagreements before a crisis approaching what the game played ever unfolds.
3. To hedge against possible nuclear attacks against low-Earth orbiting systems, the United States and its space-faring allies should develop alternatives both in other space orbits and on Earth. Devising space systems that can operate in several different orbits without major modifications or dramatically increased costs would be extremely useful to cope with the threats posed in the game. Such systems could afford the United States and its allies much greater levels of space system resiliency against both nuclear and nonnuclear threats. Such systems would also allow much greater operational flexibility in determining what an “optimal” constellation might be. Finally, it would make any reconstitution efforts much quicker and, possibly cheaper. Meanwhile, on Earth, it would be useful to fortify land and sea cable communication systems, ground-based navigational aids, and the development of alternative imagery systems mated to high-altitude balloons, long-endurance drones, or other non-space platforms. These land and air-based systems could be useful as stop gaps if low-Earth orbit space systems are disabled. In developing these alternative systems, it also would be most useful to develop ways to defend them both passively and actively.
4. Two large unknowns worth assessing are what can and cannot be done to verify the presence of nuclear weapons in space and what a military proportionate action might be to a nuclear detonation in space. There was considerable debate about America’s ability to verify a nuclear payload in space. Some thought it would be possible by 2029; others doubted this. Several questioned if without a large fleet of such inspection systems constantly in orbit, one could get close enough soon enough to make any difference if a nuclear threat arose. Whatever the truth may be, it is critical to determine what’s possible so that reasonable expectations can be set before a crisis occurs. It is always tempting to spend significant amounts of time and money to try to secure a technical fix for such a challenging detection mission. It may more sense, however, to design technically and militarily around the probability that such a fix may long prove elusive. Yet another mistaken assumption the game revealed was that agreed, proportionate military counterstrike options to a nuclear detonation in space would be on tap. They were not. Again, it is unclear what, if any, these options might be.

 

To view the full occasional paper click here.