Seems doubtful that you can make an ICBM stealthy given the launch detection systems out there and heat signature.
Regardless, it’s time to upgrade our ICBMs. The SLBM’s are still good, but the ground based leg is awful.
I’d also work out a treaty for some testing to make sure these old things still work.
Unless you didn’t use a missile. A projectile from a rail gun would do the trick.
The missile’s warheads are stealthy during sub-orbital/orbital flight and re-entry. We won’t know what hit us.