Missile defense appears as a topic of intense international debate every ten years. This happened in the 1960s and 1970s prior to the signing of the ABM Treaty (Anti-Ballistic Missile Treaty) ; in the 1980s with the Strategic Defense Initiative (SDI) ; and in the 1990s, following the Gulf War, with the GPALS project (Global Protection Against Limited Strikes). Today the NMD project (National Missile Defense) - re-designated MD (Missile Defense) or BMD (Ballistic Missile Defense) with the arrival of the Bush Administration - might well, unlike its forerunners, be progressively deployed. It could re-map strategic relations among the main world players, especially after the 11 September terrorist attacks.