bobbymike said:
It is interesting to speculate that due to an expanded target set if you include countries like N Korea, China and Iran the MMIII replacement might have to be larger than the MMIII. The first post on this thread says a range up to 26,000km is needed for truly global reach. Combined with the 'desire' to have D5 replacement commonality are we going to get an 83" diameter ICBM?
There are targets in the current portfolio that can only be held at risk by nuclear weapons - and many of those targets are not worth crossing that threshold. This is one of the (many) reasons that DoD wants alternatives like conventional prompt global strike. Given the current political climate that alone may push the US to develop new ballistic missiles, with conventional warheads as well as high precision unconventional warheads. As it is now, a conventional strike capability could be had in the near term by tail kit upgrades to Trident and Minuteman, but politics is not letting that happen.
So instead we may get a conventional strike missile, and *possibly* a new ICBM. If the SSBN-X gets enough momentum, a new SLBM is also possible.