One option within the range of possibilities in this regard is a convention to ban space-based weapons - defined as damage causing mechanisms (not associated elements such as sensors or command and control) actually based in space (not just transiting, like missiles or space planes).

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Baines, Phillip and Robert McDougall. "Military Approaches To Space Vulnerability: Seven Questions." Future Security in Space: Commercial, Military, and Arms Control Trade-Offs. Ed. James Clay Moltz. Monterey, CA: Center for Nonproliferation Studies, 2002. [ 4 quotes ] [ page 16 ]