This series, Space in Focus, explores key space trends, challenges, and policy issues that will confront the next administration as well as offers recommendations for how to navigate them.
Representative Mike Turner (R-OH) shocked much of Washington in February 2024 when he sent a memo to colleagues in Congress urging them to review sensitive intelligence warning that Russia may be preparing to deploy a nuclear weapon in space. As chairman of the House Permanent Select Committee on Intelligence, Turner later added that he was “was concerned that it appeared that the administration was sleepwalking into an international crisis.” In the weeks and months that followed, the Biden administration largely confirmed Turner’s characterization of the threat, and at a CSIS event in May of 2024, assistant secretary of state for arms control Mallory Stewart seemed to identify a specific Russian satellite that was part of the Russian program, although the information provided did not clearly support the assessment or give insight into Russia’s true intentions.
Regardless of the confidence level of the intelligence, the stakes involved are too high to ignore. Any use of a nuclear weapon in space would have broad, severe, and indiscriminate effects for every nation that relies on space. Moreover, this kind of attack could undermine the very foundation of U.S. military power projection capabilities. Rather than panic or cower before the threat, the next administration must rebuild deterrence against this type of threat using history as its guide.
While the Turner memo may have been a wake-up call for some in Washington, the threat of a nuclear attack in space is not new. The Soviet Union tested this capability four times in the early 1960s at altitudes above 100 kilometers (km), which is generally regarded as the lower bound of space. Two of these tests occurred during the Cuban Missile Crisis. The United States also detonated nuclear weapons in space in the early 1960s, which is why we know just how terrible the consequences would be. In the Starfish Prime test on July 9, 1962, the United States detonated a 1.4 megaton warhead at an altitude of 400 km over the Pacific—that is nearly five times the size of the largest Soviet tests and a factor of 100 larger than the bomb dropped on Hiroshima.
The effects from the Starfish Prime experiment were stronger and more extensive than expected. Rather than merely producing a large electromagnetic pulse, the blast left a high level of radiation in low Earth orbit that lasted for several months. This radiation degraded the electrical components of satellites, such as solar cells and radios, causing some of them to fail prematurely. David Larson at Lawrence Livermore Nation Laboratory estimated that the Starfish Prime test caused at least one-third of satellites in space at the time to malfunction in the weeks and months following the test.
What the United States and the Soviet Union learned from these tests is that using or even testing nuclear weapons in space is in no one’s interest because the effects are broad and indiscriminate. In August 1963, the United States, the Soviet Union, and the United Kingdom (which lost its first satellite to the Starfish Prime test) signed the Partial Test Ban Treaty, which prohibited any further testing or use of nuclear weapons in space. The Outer Space Treaty of 1967 further extended this prohibition, banning the stationing of nuclear weapons in orbit.
Despite these treaties, the nuclear-armed nations of the world retained their ability to use nuclear weapons in space. This is because the intercontinental ballistic missiles used to launch nuclear warheads against targets on Earth can also be used to loft and detonate nuclear weapons in space. This latent capability is not banned by treaty as long as it is not tested in this manner. And it is arguably easier for less-developed nuclear powers, such as North Korea, to launch and detonate a nuclear weapon in space than trying to hit a target on Earth because the warhead does not need to survive the heat and guidance challenges of reentry.
Deterrence held in space throughout the Cold War because each side knew that using a nuclear weapon in space would be perceived by the other as a prelude to nuclear war on Earth. The fact that Representative Turner and many others in Washington are so alarmed about the latest intelligence is an indication that the United States now doubts its ability to deter Russia from using a nuclear weapon in space, and that is more concerning than the intelligence itself.
The next administration should not continue to tolerate such an intolerable situation. It should leave no room for doubt in the minds of Russia, U.S. allies, or the American people that the United States can still deter a nuclear attack in space. It must reestablish a credible deterrence in space by building on the same foundation of deterrence that successfully prevented the use of nuclear weapons for nearly eight decades: the United States’ unmatched network of alliances.
As the conflict in Ukraine has demonstrated time and again, Russia is scared of NATO. It has gone out of its way to avoid strikes against NATO forces or on NATO territory. Russia has repeatedly threatened to use nuclear weapons in Ukraine if certain “red lines” were crossed, yet many of these lines have been crossed and nuclear deterrence has continued to hold. Russia knows that using a nuclear weapon in Europe—even if it is not against a NATO member—would bring the wrath of the alliance against it.
The next administration should take what works and extend it to space. It should begin working within NATO right away to gain support for a declaration at the next NATO summit in June 2025 that addresses the Russian nuclear anti-satellite threat directly. The statement should be simple, concise, and strong—a single sentence would be sufficient. It should state in unequivocal terms that any use of a nuclear weapon in space will be regarded as a direct nuclear attack against all NATO member states and will warrant a direct and proportionate response. It does not need to be specific about what kind of response would be used because that will depend to a great extent on the specific circumstances of an attack, but a nuclear response would certainly be on the table. And it should not stop with NATO—the next administration should pursue similar bilateral statements with our major non-NATO allies, particularly Japan, South Korea, and Australia.
Any nation that may seek to destabilize the world by using or threatening to use a nuclear weapon in space must understand that it will not work to their advantage. In an instant, they will turn the rest of the world against them, and they will suffer much greater military and economic losses on Earth than any gains they may hope to achieve in space. While the United States cannot be certain of Russia’s intent, it can make Russia certain about its intent. The next administration, in lockstep with its allies, should make it crystal clear to Russia—and all other nations—that a nuclear attack in space will be regarded no differently than a nuclear attack on Earth.
Todd Harrison is a senior fellow in the Foreign and Defense Policy program at the American Enterprise Institute.
