there's also the warhead block. i.e. the "stage" to which the warheads are attached as they descend from whatever cruising altitude the rocket reached. this block also has propellant and it's the last "non warhead" thing to fall away.  look at "post boost vehicle" in pic rel. it travels with the warheads until point of separation over target. it then has to fall somewhere. anyway, this is all just osint speculation. it's fun though!
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