Are stealth ballistic missiles possible? Quite possibly yes.
All those systems rely on large radars. also they are mainly midcourse defense systems.
Yes they hit once in a while an icbm that has decoys attached but in actual scenario to take out many interceptors needs to be launched for single ballistic missile.
one solution is currently at the development stage, maneuvring hypersonic vehicles as terminal stages like the technology China tested also negates the current midcourse abm systems as the interceptors are not maneuvrable enough to hit moving and fast target at that level.
Some use maneuvrable ballistic missiles changing trajectories so on, Chinese anti ship ballistic missile and iskandar ballistic missile of Russia are the operational types.
In my opinion another option also exists other than the hypersonic vehicles to fool the abm radars as well.
*Why not make the ballistic missile stages like matrushka dolls.
opening and releasing the terminal reentry stage at the end before antering the atmosphere.
- first stage normal ballistic missile or icbm
- second stage above atmosphere in space there is no need for aerodynamics and no friction.
what is released from inside the ballistic missile can be an object of any shape and cross section in space.
The nose of the ballistic missile can open and release the carrier object.
This object can carry the reentry vehicle inside.
There is no need for decoys.
radar absorbant material needs to be used on the carrier object and cross section should not be circular like cylinder. For example a less reflective radar cross section shape like rhombus can be chosen for the carrier object.
Thus the carrier object carrying the reentry vehicle inside is not detecteble by radar. or at least much more difficult to track than current measures.
- Terminal stage like matrushka dolls the object will open again and releasing the reentry vehicle inside before entering atmoshpere . this ofcourse is detectable but just at the end when the missile is fast enough and enemy does not have time to respond to it.
This way in my opinion sending an irbm would get over from most defenses prepared for 80s concepts. Taking out the large immovable abm radar is enough for the remaining missiles that dont need such protection. or after abm radar send several missiles to take out the airbases nuclear sites and strategic targets then launch the remains.