Space weaponisation is generally understood to refer to the placement in orbit of space-based devices that have a destructive capacity. Many experts argue that ground-based systems designed or used to attack space-based assets also constitute space weapons, though are not technically part of the “weaponization of outer space” since they are not placed in orbit. Some also argue that weapons that travel through space in order to reach their targets, such as hypersonic technology vehicles, also contribute to the weaponization of space. Many elements of the US ballistic “missile defense” system currently being developed or planned could constitute space weapons as well, as many possess “dual-use” characteristics, allowing them to destroy space assets as well as ballistic missiles.

The overwhelming majority of UN member states are concerned that the weaponisation of outer space will lead to an arms race and insist that a multilateral treaty is the only way to prevent it. There are currently a number of international initiatives underway aimed at preventing an arms race in outer space, increasing transparency and confidence-building measures, and preventing debris and violence in space.