I started simple by creating a blank scenario and placing a Soviet Delta IV class SSBN off the US East coast. Then I put a cluster of 3 targets/facilities in the middle of the country - Ohio maybe?
In the image below you see the SSBN has launched a single SLBM (Submarine Launched Ballistic Missile) that has 4 warheads/re-entry vehicles.
"A multiple independently targetable reentry vehicle (MIRV) is a ballistic missile payload containing several warheads, each capable of hitting one of a group of targets." (Wikipedia)
At this point the SLBM is at approx 265 miles altitude and 5000 knots and still ascending.




















