A potential solution to the problem of MIRV is to attack the ICBMs during the boost phase before the warheads have separated. This destroys all the warheads with a single attack, rendering MIRV superfluous. Additionally, attacking during this phase allows the interceptors to track their targets using the large heat signature of the booster motor. These can be seen at distances on the order thousands of miles, given that they would be below the horizon for a ground-based sensor and thus require sensors being located in orbit.