Recently, I came across this article
which analyzed the counterforce capability of DT SLBM, specificially trident D5-II, against hardened silo targets.
The most important takeaway, which I don't think has been discussed on the forum before, is the MASSIVE accuracy penalty for the RV when fired in a depressed trajectory.
View attachment 127123
As shown above, the range (R) and cross-range (CR) dispersion can increase by more than an order of magnitude when fired in a depressed trajectory. CEP can be approximated by CEP=0.59*(R+CR).
I modeled single-shot kill probability(SSKP) using the model from
with the 450kt W88 warhead for a range of CEP and silo hardness values.
View attachment 127124
This suggests that appropriately hardened Chinese ICBM silos (e.g. 10,000 psi, red line above) are very survivable against existing depressed trajectory trident counterforce strike fired from the Indian Ocean. In fact, it is very likely that the hardening level of the new Chinese silos are designed specifically to be survivable against DT SLBMs.
The inaccuracy is due to an RV having to travel through more atmosphere when reentering at a shallower angle. According to the paper, the range inaccuracy is proportional to 1/sin^3(a) and the cross-range inaccuracy is proportional to 1/sin^2(a).
View attachment 127128
Using this, it is possible to approximate the accuracy penalty due to depressed reentry angles relative to a normal minimum energy/maximum range trajectory reentry angle of 30 degrees (which corresponds to a CEP of 100m).
It is possible for the US to correct the atmosphere induced inaccuracy and vastly improve CEP by designing a maneurvering RV. However, this would require flight tests and cannot be deployed quickly.