The United States military must be prepared to engage in combat on or near the moon, according to General Dan Caine, Chairman of the Joint Chiefs of Staff. Caine stated that the Joint Force needs to adapt to fight, endure, and win in "global contested environments, from the seabed to cislunar space," emphasizing that "today’s modern battlefield operates from the seabed to cislunar space."
His remarks, delivered at the Air, Space, and Cyber Conference, come as the U.S. has confirmed the deployment of a secretive space weapon in Earth's orbit. The term "cislunar" itself carries ambiguity regarding its precise definition in U.S. law, potentially encompassing the region just outside the moon or the lunar surface itself.
Existing international agreements, specifically the Outer Space Treaty of 1967, prohibit the establishment of lunar military bases and restrict weapons testing or military exercises on the moon to exclusively peaceful purposes. Military personnel on the moon are permitted only for scientific research or other peaceful endeavors under the treaty.
Concerns about potential lunar or space conflict are fueled by the ongoing strategic rivalry between the U.S. and China. Space law professor Aaron Brynildson expressed to Defense One that the U.S. requires enhanced capabilities in cislunar space to ensure Chinese compliance with existing obligations and to prevent the militarization of the moon. He noted a significant "coverage gap by the U.S. that needs closing."
Brynildson also posited that it might be too late to clarify existing space law regarding military actions beyond Earth, suggesting that "the first space conflict might be the time when most of these rules get written."