The United States, China, and Russia have not ratified an additional agreement to the Treaty on the Principles of the Activities of States in the Exploration and Use of Outer Space, prohibiting military activities on the Moon, according to the American edition of Defense One.

The publication claims that there are a limited number of locations on the moon that are suitable for hosting inhabited or visited bases. According to Defense One, China or Russia, by placing their bases in economically advantageous places, can organize a security zone around them, where U.S. access will be restricted.

The publication admits that this circumstance may provoke military actions, which will require the protection of US assets at a distance of 272 thousand miles (about 438 thousand kilometers) from the Earth.

“In the future, other defensive and offensive means will be required to ensure the open and peaceful use of near-lunar space,” Defense One quotes the opinion of space systems engineer Laura Duffy and lawyer James Lake.