The former problem was becoming increasingly apparent beginning in approximately 1957. Missiles designed to carry a specific warhead began having increasing levels of excess throw-weight as warhead physics improved missile design, resulting in smaller and lighter warheads. Even a small amount of excess capacity could be used to carry radar decoys or chaff, which is very light weight, and would create additional radar returns that would act indistinguishably from those of the real warhead, in the airless, exo-atmospheric vacuum, of sub-orbital space; where the missile intercept was planned.