Sagan spoke out against the project, arguing that it was technically impossible to develop a system with the level of perfection required, and far more expensive to build such a system than it would be for an enemy to defeat it through decoys and other means—and that its construction would seriously destabilize the "nuclear balance" between the United States and the Soviet Union, making further progress toward nuclear disarmament impossible.
Sagan opúxose ó proxecto, argumentando que era tecnicamente imposible desenvolver un sistema semellante co nivel de perfección requirido, e que sería moito máis caro elaboralo que para un inimigo eludilo mediante reclamos ou outros medios, e que a súa construción desestabilizaría seriamente a balanza nuclear entre os Estados Unidos e a Unión Soviética, tornando imposible calquera progreso cara ó desarmamento nuclear.