Both R-7 and Atlas SM-65 were difficult to keep in a state of launch readiness and were not capable of being launched at a moment's notice (unless a "moment" is

Both R-7 and Atlas SM-65 were difficult to keep in a state of launch readiness and were not capable of being launched at a moment's notice (unless a "moment" is between 6 and 12 hours). This was somewhat expected as they were essentially "version 1.0" of the ICBM launch vehicle. Later generations were considerably improved.