The strategy seems to be different today. Gf-0012
I think the reason for giving up the defece of the US cities is that it probably wouldn't have worked once the Soviets started MIRV the Missiles.
The Strategy today is as far as I can see:
Kill the russian missiles and planes BEFORE they get within range to do damage:
1. The bombers will not stand a chance of reaching the CONUS - and haven't had that chance for a long time.
One of the Air-air tasks of the F-22 is to pick out the Bears and Backfires before they reach CANADA. The F-22 has the speed and range to do that - and a bomber isn't that maneuvrable a target. so they will be picked out of the air as soon as they leave their own fighter cover. The F-15 ca´n do that as well; but that takes a presense on Iceland. Now they have stood down Keflavik, which indicates that the other methods are deemed more than sufficient.
2. The Russian boomers will probably imitate Kursk: According to Russian complaints, the russian submarine crews cannot hear themselves think for all the pinging the LA-class is doing just outside their doorstep.
Secondly - if I'm not wrong - there are tracking devises on the polar seabed - not just a line that will register the passage of a sub; which will then get a LA glued to it. No we are talking a system that will allow attack subs to be directed pretty much like an air defence fighter. The extend of that problem is indicated by the construction of only 3 Seawolf class: They have the speed and depth needed for that mission as interceptors - typically Jimmy Carter has been put on kitchen patrol.
The connection between the oceans is probably cut, which explains the Russian emphasis on seagoing minesweepers - and the upgrading of Chilean and other nations frigates. A minefield has to be defended to be effective.
3. The ICBM's are located with idiotic precision, and You can be pretty shure they are all found and accounted for: You don't build concrete construction of that magnitude without revealing yourself on a satelite photo.
There is the real mission of the B-2: Take out the siloes before those birds fly!
Just look at the bunkerbuster bombs they carry. Here is also the offensive mission of the F-22: They are to perform fighter sweeps to clear the path for the B-2 for hostile fighters and radars. The problem is not the flying time of the missiles, it is the time to prepare them for launch. These siloes are to be taken out during the process of preparing the missiles for launch.
No system is 100% foolproof, so there has to be a backup in case a couple of missiles to take of - either from an overlooked sub or a from a silo, that escapes destruction. This is what the missile defence system is for: The system is probably to small for handling a full scale attack on its own; the trick is that it will never need that. The task is to polish off the leftovers from the other methodes of capability reduction - and with this mission it seems well worth while.