Sebastian Brixey-Williams

Sebastian Brixey-Williams is the Executive Director of BASIC, an independent, non-profit think tank based in London whose mission is to safeguard humanity and Earth's ecosystem from nuclear risks and interconnected security threats, for generations to come. He is a Fellow at the Harvard Belfer Center’s Managing the Atom Program, and an Honorary Research Associate at the School of Government at the University of Birmingham.

Sebastian’s research and practice centres around how to ensure that nuclear-armed states manage their nuclear weapons in as legal, morally-responsible, and transparent manner as possible, while advancing multilateral efforts towards a more sustainable global security system that does not rely on nuclear deterrence. His research at Harvard (2024-2025) uses a foresight methodology to examine the evolution of international law into the near future, and its possible impact on states’ nuclear targeting policies.

Sebastian regularly advises world-leading forums for discussion on nuclear weapons policy and diplomacy, including the P5/N5 Process, the UN Secretary-General’s Advisory Board on Disarmament Matters, the UN Secretary-General’s High-Level Advisory Board on Effective Multilateralism, and three All-Party Parliamentary Groups in the British Parliament. Since 2023, he has served as one of three British delegates to the Expert Level Track to the P5/N5 Process. He is regularly invited to speak at universities, most recently by Harvard, Oxford, and Stanford.