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Cislunar Security: U.S. and Chinese Activities in Cislunar Space and
Future Issues
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FUKUSHIMA Yasuhito and YATSUZUKA Masaaki
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Abstract
Discussions focusing on cislunar security have started to gather momentum. It is due to the increasing
potential for cislunar space to evolve into a location of continuous human activity and both the
United States and China see implications here beyond science and technology. In this context, the
U.S. Department of Defense is establishing technology demonstration programs as well as a unit
associated with cislunar space, with a focus on space domain awareness. China’s People’s Liberation
Army has indicated in one of its current textbooks that it believes the military domain will extend
into deep space, and it has been suggested that the military may have been already assigned related
missions. In preliminary considerations of future cislunar security, three issues can be raised for
possible military activities: support of military activities on Earth and inside geosynchronous orbit,
protection of national interests in cislunar space, and the defense of lines of communication and relay
stations to deep space. Concerns to be discussed regarding the governance of cislunar space include
space debris, space situational awareness, space trafc management, lunar resource development,
and the activities of military organizations and personnel on the Moon.
Introduction
In recent years interest in cislunar space has grown for the rst time since humans rst landed on
the Moon about half a century ago. Cislunar space literally means the space on this side of the
Moon (in Latin, “cis” means “on this side of”). This includes the area of space from the Earth to
geosynchronous orbit (GEO), but generally, the area within GEO is excluded when discussing
cislunar space.
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On the other hand, denitions of cislunar space often include the ve Earth-Moon
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Originally published in Japanese in Anzenhosho Senryaku Kenkyu [Security & Strategy], vol. 3, no. 2 (March
2023). Some parts have been updated.
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Senior Fellow, Global Security Division, Policy Studies Department, NIDS / Senior Fellow, China Division,
Regional Studies Department, NIDS
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In many cases, GEO refers to geostationary orbit, about 36,000 km from the Earth’s equator. For a denition of
cislunar space, see the examples below. Ofce of Science and Technology Policy, The White House, National
Cislunar Science and Technology Strategy, November 2022, p. 3, https://www.whitehouse.gov/wp-content/
uploads/2022/11/11-2022-NSTC-National-Cislunar-ST-Strategy.pdf; Steve Parr and Emma Rainey, eds.
“Cislunar Security National Technical Vision,” Johns Hopkins University Applied Physics Laboratory, November
2022, pp. 1-2, https://www.jhuapl.edu/Content/documents/CislunarSecurityNationalTechnicalVision.pdf.
