Credit: SpaceNews/Midjourney

A comparison of two recent wargames reveals that the United States’ current course of action to ensure space resilience may not adequately deter and defend against emerging new Chinese space threats beginning around the mid-2020s. However, these wargames suggest a practical way forward for timely space resilience in the 2020s and beyond.

On Jan. 10, the Center for Strategic & International Studies (CSIS), a Washington think tank, issued a 165-page report stating that “CSIS developed a wargame for a Chinese amphibious invasion of Taiwan [in 2026] and ran it 24 times. In most scenarios, the United States/Taiwan/Japan defeated a conventional amphibious invasion by China and maintained an autonomous Taiwan.”

That the United States is likely capable of defeating China in the “pacing scenario” for the U.S. military is reassuring news, especially coming on the heels of Russia’s military adventurism in Ukraine and President Xi Jinping’s consistent advancement of the timetable for the People’s Liberation Army (PLA) to achieve a sufficient military capability to credibly seize Taiwan.

On the other hand, while the costs of aiding Ukraine to fend off Russia are already high, the costs of helping Taiwan to fend off China are likely to be far higher. China’s economy is about six times as large as Russia’s and much more deeply embedded into global commerce, complicating sanctions and increasing collateral damage. And even military “victory” would come at a high price. For example, the U.S. would likely lose between 12 percent and 40 percent of its operational inventory of fighter aircraft within a few weeks. At the same time, Taiwan is a vital strategic foothold for access to the wider Pacific, and is home to some 92% of the world’s capacity in manufacturing the most advanced semiconductor. Additionally, Taiwan is a bastion of democracy and a “canary in the coalmine” regarding both global norms of sovereignty and China’s intentions in the region.

Crucially, the outcome of any wargame depends on its underlying assumptions. The CSIS study was methodologically robust and quite transparent regarding the assumptions and parameters adopted. One of the most consequential “Major Assumptions” expressly identified in the report was that China’s antisatellite (ASAT) weapons are “moderately effective.” In particular, this assumption was based on a “lack of historical evidence” and the judgment that “co-orbital interference will take longer than…a month.” This determination bears mightily on the resiliency of the U.S.’s space architecture, but another recent wargame calls it into question.

In June 2021, the Nonproliferation Policy Education Center (NPEC), a nonpartisan think tank run by former Pentagon official Henry Sokolski, sponsored a China Space Wargame set in the 2027-2029 timeframe. The NPEC wargame assumed that, in the first move, “PRC [People’s Republic of China] initiated space control operations intended to weaken U.S. regional allies (e.g., Japan, Republic of Korea (RoK), Australia) resolve in opposing a PRC economic exclusion zone enforcement effort against Taiwan.” Over two dozen wargame participants, with diverse ideologies and experiences, proposed and responded to a variety of potential ASAT threats. Ultimately, the report found that a key variable likely to affect the makeup, usability, and impact of the PLA’s ASAT capabilities is whether or not the United States and its allies ready — and publicly declare — adequate legal and technical counters to the use of hostile rendezvous-and-proximity operations (RPOs).

Following intensive discussions and in the 2029 scenario, the initial wargame employed a rough estimate of 108 Chinese small spacecraft capable of such dual-use RPOs (or R-spacecraft) — 100 designed for dedicated ASAT use, plus an additional eight repurposed from satellite servicing and space debris removal missions. In August 2021 and March 2022, this estimate was revised to about 200 R-spacecraft by 2026, following China’s accomplishment of numerous technical milestones — the most notable of which was successfully docking with a non-responsive satellite in a geosynchronous orbit (GEO) and maneuvering it to a higher orbit. This capability was demonstrated in January 2022, some three years ahead of the timeline estimated in the original NPEC wargame and less than two years behind U.S. commercial space companies first doing the same with a willing satellite. 

Adopting this estimate of 200 R-spacecraft in 2026 — which is the same year chosen for CSIS’s Taiwan wargame — China would likely be capable of disabling most of the three dozen Global Positioning System (GPS) satellites in medium earth orbit (MEO) in rapid succession at the opening of a war. Moreover, China would likely still have many R-spacecraft left over to disable or interfere with other critical-but-vulnerable satellites housed in GEO and highly elliptical orbits (HEO). These include, for example, key communications, imagery, and meteorology satellites and the highly sensitive missile-warning satellites and communications satellites supporting the U.S.’s nuclear and conventional forces.

Such attacks might well impact the outcome of a Taiwan contingency. Even if they did not, they would generate unique escalation risks, as well as directly increase the costs of any military engagement. The temptation to conduct such attacks early in a crisis, given both the operational impact and the potential to coerce the U.S. into backing down entirely, could be immense. The CSIS report outlines that one of the four conditions for success is that “the United States must be able to strike the Chinese fleet rapidly and en masse from outside the Chinese defensive zone.” Such operations become substantially more difficult with severely degraded GPS capabilities, which would make it much more difficult to accurately locate Chinese targets, as well as to guide precision munitions to targets (e.g., ships in the Chinese fleet).

These potential vulnerabilities are not yet being addressed, though there are efforts in that direction. Gen. John W. Raymond, first Chief of Space Operations, ordered in November 2020 that the Space Warfighting Analysis Center (SWAC) be established to develop “future force design options.” The first force design from SWAC was a proliferated missile-warning and missile-tracking architecture. In September 2022, Space Development Agency (SDA) Director Derek Tournear reaffirmed that, after the three GEO satellites are launched, “the future will all be proliferated LEO [low Earth orbit] with a semi-proliferated MEO to give you that resilience.” While a highly positive step, transitioning to such an architecture will take time: a detailed analysis published Jan. 3 shows that vulnerability will persist at least until the end of the decade, if not longer. Thus, the vulnerability of these constellations for the 2020s remains a serious problem that the DoD must confront and resolve. The commercial sector, via such as space traffic management, can contribute to this goal in various ways, but only if clear corrective actions are taken soon; a Taiwan contingency might well be only a few years away. 

Wargames do not provide immutable facts about the world but rather provide a means of testing the likely consequences of a given set of assumptions. Comparing both the findings and the stated assumptions of these two recent wargames from CSIS and NPEC leads to the conclusion that the U.S. coalition would likely win a war over Taiwan fought in 2026 — but only if the U.S. and its allies and partners ready adequate defenses against Chinese ASAT capabilities within the next three to five years, particularly the pre-positioning and use of China’s likely R-spacecraft arsenal.

However, should the U.S. fail to do so, such a contingency will, at best, be fraught with greater risks of nuclear miscalculation and a significant increase in expected loss of life, military platforms, and commercial assets; and, at worst, may end with a successful forced reunification of Taiwan and mainland China.

The recommendation from the comparison of two wargames, therefore, is that DoD should continue to transition vulnerable space systems to proliferated constellations, whenever resilience can be attained by doing so; as well as ready tailored defenses to emerging new ASAT threat vectors. Given the magnitude of the potential consequences, even a low probability would be sufficient to warrant appropriate preparations—and the probability might well be much higher. To do otherwise would be to fail to uphold the U.S.’s commitment to the Taiwan Policy Act of 2022, which “affirms U.S. policy to oppose any attempt by the PRC to unilaterally impose a timetable for unification on Taiwan.”

Brian Chow (Ph.D. in physics, MBA with distinction, Ph.D. in finance) is an independent policy analyst with more than 170 publications. He can be reached at Brandon Kelley is the director of debate at Georgetown University, and a graduate student in the Security Studies Program. He can be reached at

Brian Chow (Ph.D. in physics, MBA with distinction, Ph.D. in finance) is an independent policy analyst with more than 170 publications.