1. The U.S. no longer maintains a command post on continuous airborne alert. There are two planes on 15 minute ground alert, but they are very vulnerable sitting on a limited set of alert facilities.
2. A couple of new submarine detection methods have gotten some development. Signal processing for sonar has improved.
3. Missile accuracy has improved, particularly in a first strike scenario where satellite navigation would be available.
4. Aerial drones have gotten much more sophisticated and compact, which could jeopardize silos, communications infrastructure, bombers on the ground, and the E-6s and E-4s.
5. Sea based drones have undergone extensive development and might become a serious threat to the submarine force.
6. Anti satellite weapons have advanced significantly, putting communications satellites to transmit launch orders at risk.
7. There has been more work on maneuvering reentry vehicles and hypersonics, which could enable depressed trajectory launches which, if they were accurate enough to destroy silos or the underground launch control facilities, could knock out the ICBMS with less than 10 minutes of warning, which is not enough to retaliate in time.
