You only need a very small number of doomsday devices in order to allow arbitrary delay for retaliation after first strike. Ten sleeper agents with extreme bio

You only need a very small number of doomsday devices in order to allow arbitrary delay for retaliation after first strike. Ten sleeper agents with extreme bio weapons in the likely aggressor country, for example. There is no purpose in rushing to doomsday and a great deal of interested parties in not doing so.