At the requests of the House Armed Services Committee and the Senate Foreign Relations Committee, OTA undertook an assessment of the opportunities and risks involved in an accelerated program of research on new ballistic missile defense technologies, including those that might lead to deployment of weapons in space. The resulting report,'Ballistic Missile Defense Technologies', is being published concurrently with this volume. This report on 'Anti-Satellite Weapons, Countermeasures, and Arms Control' ...