The United States has confirmed it has deployed weapons in space for the first time, with military officials telling troops to prepare for potential combat from the seabed to the region of space surrounding the Moon.
General Dan Caine, chairman of the Joint Chiefs of Staff, issued the warning to military personnel and industry figures at the Air, Space and Cyber Conference near Washington DC on Wednesday, September 16. He said the US military must prepare immediately so it is ready to "fight, endure and win... from the seabed to cislunar space."
Space Force gearing up for warfare beyond Earth
America's Space Force, established by President Donald Trump in 2019, is already preparing for potential battles in space and around the Moon as "humanity is advancing deeper into space," according to Lt Gen Gregory Gagnon, head of its Combat Forces Command. He said the Space Force's mission is to "help be prepared to defend US interests."
The comments came days after Air Force Secretary Troy Meink confirmed at the same conference that the US has deployed "on-orbit space control weapons," confirming something many had long suspected.
China responds to space weapons announcement
The revelations have raised fresh questions over longstanding international agreements intended to keep space peaceful and demilitarised. The US and several other nations have already demonstrated the ability to destroy satellites orbiting Earth, although those tests have so far involved weapons fired from the ground at their own satellites.
Lt Gen Gagnon said America's intelligence community had made clear that potential enemies were attempting to take warfare into space. "The intelligence community has been clear that potential adversaries have been seeking to extend warfare into space," he said. "Our potential adversaries, such as the PRC, are actively pursuing activities in the system, in parts of space," he added, referring to the People's Republic of China.
China established its own military space forces in 2024, giving them responsibility for strengthening the country's ability to respond to space-related crises. Beijing has hit back at America's announcement, with Chinese foreign ministry spokesperson Guo Jiakun saying on Tuesday that "China always upholds the peaceful use of outer space, maintains outer space security, and opposes the weaponisation, militarisation, and an arms race in outer space." He also urged the US to "stop expanding its military preparations in outer space."
International treaties and Space Force expansion
Exactly what America's new space weapons mean for international treaties remains unclear. The 1967 Outer Space Treaty, signed by both the US and China, says celestial bodies, including the Moon, must be used "exclusively for peaceful purposes." The treaty also prohibits weapons being stationed in space and states that countries remain "liable for damage caused by their space objects."
The issue has already sparked international tensions. Two years ago, efforts to strengthen UN measures against the militarisation of space gathered pace after US intelligence suggested Russia was developing a space-based weapon. Russia blocked a joint US-Japanese resolution calling on nations not to develop or deploy nuclear weapons or other weapons of mass destruction in space, which are prohibited under the treaty. A rival Russian resolution seeking to ban all weapons in space "for all time" also eventually collapsed.
Asked about the 1967 treaty and other international commitments, Gagnon said the Space Force "will continue to execute safe and responsible space operations in all the reaches of space." He refused to go into detail about whether the Space Force or wider US military could deploy weapons such as bullets or projectiles in space, instead directing questions to the Pentagon.
The US military is planning a major expansion of its space forces. Gagnon revealed the Space Force is expected to double in size over the next five years, reaching around 25,000 personnel. Around two-thirds of the expansion will be focused on the Combat Forces Command. "We have capabilities in the military because we are preparing to defend the nation," Gagnon said. "The reason we have the capabilities is to help create deterrence."
