Pasta,
Good call - SLBMs buy time to confirm a strike is inbound and if it is, to negotiate from a position of (relative....) strength after the first exchanges by ICBMs/IRBMs have been completed...if, of course, anyone is left. The First Strike strategy, e.g. Counter-force, Counter-value or Decapitation can be analysed and an appropriate response ordered - assuming links are available. If, however, the aggressor has achieved decapitation he must reckon that, at some stage in the near future, SLBMs will start launching. This is the key role for the SLBM, that of assured penetration vice SLCMs, and is why Deterrent has worked for so long; SLBM MIRVs cannot be reliably attrited by any defence mechanism yet deployed. DEW based defence systems may well spell the end for the SSBN/SLBM combination but that's probably 30 years away yet....As already mentioned, basing your deterrent on SLCMs or air launched Storm Shadow provides as much potential for mis-ID and miscalculation as would using a Trident D-5 to deliver a hyper velocity conventional kinetic weapon......"it's not a nuke, honest guv"