On 18 April 2022, Vice President Kamala Harris announced that: "The United States commits not to conduct destructive, direct-ascent anti-satellite (ASAT) missile testing."
In international law, statements such as these are called "unilateral declarations". If made in clear and specific terms by an authority vested with the power to do so, they constitute legally binding commitments vis-à-vis all other states.
Vice President Harris also indicated that the United States seeks to establish this as a "new international norm for responsible behavior in space", and called on other states to make similar commitments.
In 2021, the Outer Space Institute organized an international open letter calling for negotiations on banning the testing of all kinetic ASAT weapons, i.e. weapons that employ violent impacts and thus create long-lasting space debris.
Although we envisaged a multilateral treaty, treaties are not the only way in which international rules can be created. We commend the United States for its unilateral declaration and call on other states to make their own declarations without delay.
Aaron Boley and Michael Byers, Co-Directors, Outer Space Institute
Statement available in PDF format here.