The international space law came into effect on 10 October 1967 and it decrees that no-one is allowed to lay claim of ownership on the Moon or on a planet, as they are the common heritage of mankind.
The Outer Space Treaty is a treaty that forms the basis of international space law.
The treaty was opened for signature in the United States, the United Kingdom, and the Soviet Union on 27 January 1967. It is the basic legal framework of international space law and 102 countries are now parties to it.
It also bars the countries that have signed from placing nuclear weapons or any other weapons of mass destruction in Earth's orbit. They are also not allowed to install such weapons on the Moon or any other celestial body or station then anywhere in outer space.
The treaty explicitly forbids the use of the Moon specifically for anything but peaceful purposes. It is stated in the treaty that "outer space, including the Moon and other celestial bodies, is not subject to national appropriation by claim of sovereignty, by means of use or occupation, or by any other means."
One has to wonder: Who will control or police the space activities of the countries who did not sign the treaty?
