Terminal guidance is nessesary only if the accuracy within few tens of meters is needed . Normal nuclear warheads without terminal guidance have accuracy of 350100 m CEP . That ' s good enough for most counterforce targets like nuclear silos . Inertial navigation and celestial reference during midcourse combined with spinning the warhead to stabilize its trajectory in reentry provides that accuracy . Guidance from satellites or ground stations is optional extra . If the target is large like a city and accuracy within few kilometers is enough , warhead turns into uncontrolled and unguided maneuvering reentry vehicle with small modifications . When the center of gravity is off the centerline and aerodynamic shape of the warhead is nonsymmetric , it generates strong lateral evasive movements .