The U.S.-China Military Balance in Space

ABSTRACT

How will the U.S. military's growing use of space to support its operations and the growing counterspace capabilities available to its rivals shape the balance of power? This article develops a framework to assess the U.S.-China military balance in space and applies that framework to a Taiwan scenario. It evaluates trends in both the U.S. military's dependence on space to defend Taiwan and the resilience of U.S. satellite constellations against a Chinese counterspace campaign. The findings highlight some of the challenges that China's military modernization and expansion have created for the U.S. military, but they caution against overstating the magnitude of the threat. The findings also support qualified optimism about the future: Encouraging trends in resilience will enable space to remain a major asset rather than a major liability for the U.S. military. But the Chinese military will also benefit from these positive trends in resilience, which will create new challenges for the United States in countering China's use of space to support its own military operations.

How will the U.S. military's growing use of space to support its operations and the growing counterspace capabilities available to its competitors shape the balance of power? These two trends have contributed to a meteoric rise in concern that the United States would struggle to defend its allies and partners if adversaries attacked U.S. military satellites during a war. Since China's landmark test of a direct-ascent anti-satellite (ASAT) weapon in 2007, U.S. defense analysts have cautioned that satellites are “as vulnerable as they are essential,”¹ and that space has become “the American military's Achilles heel.”² Government officials have also issued dire warnings, such as invoking the possibility of a “space Pearl Harbor” that would leave the U.S. military “deaf, dumb, blind, and impotent.”³ This pessimistic rhetoric is often vague and unsubstantiated by technical assessments that could enable a more rigorous public debate about the scale and character of the problem.⁴ This article contributes to this debate by developing a framework to assess the U.S.-China military balance in space and applying that framework to a Taiwan scenario.⁵

The article's framework distinguishes between dependence and resilience as two key concepts for understanding the military balance in space. Dependence captures how much the United States relies on satellites to support the military operations required to defend Taiwan. The U.S. military would need to conduct certain missions to defeat a Chinese invasion, such as attacking Chinese warships and troop transports, defending airspace from Chinese fighters, and potentially striking military targets (e.g., ports and logistics hubs) on mainland China. Dependence represents the extent to which the U.S. military's ability to satisfy the operational requirements of those specific missions would decline because of degraded or denied access to space. Because satellites are not the only way to provide enabling capabilities such as communications, intelligence collection, and precision guidance, measuring dependence requires assessing how effectively terrestrial alternatives could substitute for satellites. This assessment provides a performance baseline for gauging how much degraded access to space would affect the U.S. military's ability to conduct the missions required to defend Taiwan.

Resilience captures how effectively U.S. satellite constellations can withstand Chinese counterspace attacks and still provide useful support to U.S. forces. The conventional wisdom is that the offense has overwhelming advantages over the defense in space, so much so that the “defense is impractical in the long term” against sophisticated military competitors like China.⁶ These claims tend to focus on the tactical-level survivability of individual satellites, but the more important question is the operational-level resilience of satellite constellations. Although defending any one satellite might be difficult, what ultimately matters is the resilience of networks of satellites in terms of their ability to keep providing support even as they lose individual nodes. Most satellites are just nodes in larger networks, and the importance of any one node depends on a network's characteristics. Measuring resilience requires assessing how the attributes of different satellite constellations make them more or less robust to different counterspace threats. Analysts sometimes discuss counterspace capabilities as having almost mystical or omnipotent qualities, but like any other weapon they have strengths and weaknesses rooted in the laws of physics.⁷

Applying this framework to a Taiwan invasion scenario shows some of the growing challenges that the U.S. military faces, but it also supports qualified optimism about the future. Over much of the past two decades since China's direct-ascent ASAT test in 2007, the direction of trends for U.S. dependence and resilience has been negative because China has rapidly modernized and expanded its military.⁸ The United States has developed some dependencies on space to maximize the effectiveness of its operations to defend Taiwan, and China has made impressive advances in its counterspace capabilities. But the magnitude of the challenge remains more manageable than many analysts fear.⁹ The United States' dependence on space is not so brittle that degraded access would necessarily hamstring its operations to defend Taiwan, and the Chinese counterspace threat is not so severe that China could quickly and easily deny the United States access to space. Additionally, U.S. space architectures are already becoming more resilient, reversing the direction of this previously negative trend. The shift toward “proliferated” constellations that have hundreds or thousands of small satellites along with the explosive growth of the United States' commercial space sector have been key drivers of this positive trend. The United States also has the potential to reduce its dependence on space through investments in promising new capabilities and operational concepts, though progress has not been as striking as it has with resilience.

There are two key qualifications to these findings. First, this article's qualified optimism about the future assumes that the United States continues to invest in more resilient space systems and more robust terrestrial alternatives. This article provides a more realistic and precise threat assessment, but it is not a call for complacency. Even if China's counterspace capabilities are not decisive wonder weapons, they still contribute to eroding the advantages that the United States enjoyed when it had command of the space commons.¹⁰ The return of a contested military balance across all domains reflects a return to historical normalcy in many ways.¹¹ But a smaller margin of advantage is still cause for concern because it increases the risk of deterrence failures and the costs required for victory if deterrence fails.

The second qualification to these findings is that the growth of China's satellite capabilities to enable its own operations is becoming increasingly central to the U.S.-China military balance. Some of the article's findings about the practical difficulties of counterspace campaigns that are good news for U.S. resilience against Chinese attacks are also bad news for the United States' ability to deny the military benefits of space to China. Contrary to the influential prediction that offensive advantages in space will limit the effective reach of China's precision strike networks beyond 400–600 kilometers from the mainland, China's nascent long-range kill chains will become a serious and enduring challenge.¹²

The article proceeds as follows. The first section develops an analytic framework that focuses on dependence and resilience. The second section implements this framework by assessing the extent of U.S. dependence on space to defeat a Chinese invasion of Taiwan. The third section evaluates the extent of U.S. resilience to a Chinese counterspace campaign. The conclusion considers how the Chinese military's growing dependence on space could reshape the military balance going forward.

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From International Security