A Proposal to Counter the Greatest Space Threat

Outer space is an emerging military domain. While space warfare is still theoretical, space weaponization—development of ground or space-based systems that can degrade or destroy space-based systems—is real. The most prevalent and consequential space weapons are kinetic energy anti-satellite (KE-ASAT) systems, which destroy satellites through a missile intercept (direct-ascent) or weaponized satellite (co-orbital). But, this destruction also creates thousands of collateral space debris pieces that threaten space assets from weather satellites to the International Space Station. As more nations develop KE-ASAT capabilities, a practical KE-ASAT testing agreement on reporting, liability, arbitration, and retaliation is necessary to preserve space for civil, commercial, and scientific activities.

Growing KE-ASAT Threat

During the Cold War, the U.S. and the Soviet Union fielded satellites for communications, intelligence, surveillance, and reconnaissance, but their importance—and vulnerability—made them prime military targets. Soon, the U.S. and the Soviet Union developed and tested KE-ASAT weapons, but tests stopped in 1985 after their debris-laden consequences became apparent. Described by NASA as “the greatest risk to space missions,” space debris pieces—even paint flecks—traveling at speeds of tens of thousands of kilometers per hour can damage and destroy space assets. Plus, KE-ASAT tests take place in low-earth orbit (LEO) (<2,000 km), where 66% of all satellites orbit, and the resulting debris may last for months or years, threatening countless government, commercial, and civil satellites.

In 2007, however, the testing moratorium ended. China conducted a KE-ASAT test that created 150,000 small (1-10 cm) debris pieces and 2,500 large (> 10 cm) space debris pieces. The test increased total trackable space debris by 25%, some of which will remain in orbit for decades and likely centuries. Consequently, the strategic value of KE-ASAT weapons coupled with decreasing technology costs means tests may proliferate.

Indeed, they already have.

In March 2019, India performed a KE-ASAT test that created four hundred pieces of debris and endangered the International Space Station. Some of the debris may orbit for years. Other countries such as Iran, North Korea, Pakistan, and Israel may also develop and test KE-ASAT weapons given their technological similarities with ballistic missiles.

Furthermore, China may conduct more tests—this time at geostationary orbit (GEO) (about 36,000 km) where orbital objects remain for generations. The U.S. Defense Intelligence Agency’s space report said, “China probably intends to pursue additional ASAT weapons capable of destroying satellites up to GEO.” And in 2014, China conducted a targetless ASAT GEO test. Testing KE-ASAT GEO weapons is particularly concerning as missile warning satellites are located in GEO, and a Chinese test may spur retaliatory tests by the U.S., Russia, and India to reestablish deterrence.

As space becomes more congested and contested, establishing a KE-ASAT testing agreement that restricts KE-ASAT LEO tests and bans KE-ASAT tests at other orbits is necessary to safeguard the perpetual use of space. And the world’s leading multilateral organization is the starting point: the United Nations.

Drafting an Agreement

With its space purview, proven record of drafting space agreements, and ninety-five member nations, the UN Committee on the Peaceful Uses of Outer Space (COPUOS) is the ideal forum to draft a KE-ASAT agreement on reporting, liability, arbitration, and retaliation. While the proposed agreement focuses singularly on KE-ASAT testing, similar narrow space agreements, such as the Treaty Banning Nuclear Weapon Tests in the Atmosphere, in Outer Space and Under Water, proved effective. Importantly, the proposed KE-ASAT agreement’s objective is to limit space debris accumulation by preventing debris-creating KE-ASAT tests.


The proposed agreement incorporates the Registration Convention, which requires nations to provide information on their space assets including the owner, launch date, time, and location to the UN Office for Outer Space Affairs (UNOOSA), the secretariat for the COPUOS. As part of the proposed agreement, new reporting requirements compel nations testing a KE-ASAT weapon to disclose the projected flight path, apogee, estimated debris spread, and other relevant features to UNOOSA before the test. This enables space actors to preemptively mitigate risks to their space assets. UNOOSA will monitor compliance and aggregate reporting information, laying the liability foundation for KE-ASAT debris.


Increasing space congestion has increased the likelihood for the degradation and destruction of multimillion-dollar space assets. And KE-ASAT testing compounds this risk. Establishing strict liability for space debris decreases the likelihood of KE-ASAT tests as nations are responsible for compensation if test debris damages or destroys other space assets. Fortunately, an applicable liability agreement already exists. The Liability Convention creates liability for damages caused by ground-launched space objects: “a launching State shall be absolutely liable to pay compensation for damage caused by its space objects.” Accompanying the reporting above requirements, ground- and space-based sensors can perpetually track space objects and debris and therefore attribute responsibility in a space collision. The proposed agreement simply incorporates the Liability Convention, but it does adopt new arbitration and retaliation rules.


Diplomacy is the ideal resolution to a space collision, but recourse is needed if a dispute occurs over liability or compensation total. Largely effective in international agreements, arbitration, specifically the Permanent Court of Arbitration (PCA), is the proposed agreement’s dispute resolution mechanism. PCA, an Official UN Observer, has already established “Optional Rules for Arbitration of Disputes Relating to Outer Space Activities,” and its experience in international arbitral issues such as the UN Convention on the Law of the Sea make it the ideal forum to handle space disputes. However, if the violating nation does not comply with the arbitral ruling, the proposed agreement permits alternative redress measures.


Forcefully compelling the liable nation to pay for damages is impossible; therefore, in order to prevent unencumbered retaliation, the proposed agreement utilizes economic retaliation. Partnering with the World Trade Organization, UNOOSA will calculate retaliatory tariffs by assessing the damaged or destroyed space asset’s economic value plus its related activities. David DeFrieze in his article “Defining and Regulating the Weaponization of Space” writes, “a solution might be to invoke the enforcement power of the WTO as a last resort forum if valid adjudicated claims go unpaid and diplomatic avenues fail.” Citing space’s commercial nature and the WTO’s proven enforcement power, he justifies this tariff retaliation. Despite the apparent space-tariff disconnect, satellites are economically important, and the consequences of proportional economic retaliation should limit reckless KE-ASAT testing.

Feasibility—and Necessity

A complete KE-ASAT LEO test ban is unrealistic. Nations will continue to test and employ dual-use systems such as midcourse ballistic missile defense (BMD) systems, which can perform a KE-ASAT LEO function. For example, in 2008 the U.S. destroyed a satellite with a modified Aegis midcourse BMD system. Furthermore, targetless tests—“placing a missile at an exact location at a precise time”—are possible. In the past ten years, both China and Russia have conducted ASAT tests that did not destroy a space target and therefore did not create space debris.

Banning KE-ASAT tests at other orbits, however, is possible. Tests at these orbits are clearly ASAT tests, and the subsequent debris’ longevity confers pariah status upon nations that conduct such tests. The spacefaring community has shown willingness to consider, albeit different, space arms control agreements and international codes of conduct. This engenders the possibility for a complete KE-ASAT ban at non-LEO orbits.

Global reliance on space infrastructure, especially satellites, make negotiating and implementing an agreement feasible. Depending on space militarily, commercially, civically, and scientifically, the five permanent UN Security Council members (China, France, Russia, United Kingdom, and the United States) partially or wholly operate or own 77% of all satellites. Space debris and in turn KE-ASAT tests endanger these space assets and those of other nations. The broad international reliance on space expands the feasibility in establishing a restrictive KE-ASAT testing agreement.

While solely addressing KE-ASAT tests fails to comprehensively resolve space debris, it does mitigate a major space threat: production of more space debris. If an agreement is negotiated and ratified, it might spur addressing other space weaponization challenges. And understanding the unintended consequences of these powerful weapons is the first step. After all, we should heed what Bendu in Star Wars says, “An object cannot make you good or evil. The temptation of power, forbidden knowledge, even the desire to do good can lead some down that path.”