Three factors are now shaping the evolution of the U.S. nuclear force: (1) the pursuit of nuclear-weapon reductions below current levels for all weapon types - strategic and non-strategic, deployed and non-deployed; (2) modernization of a nuclear force developed during the Cold War and shaped by Cold-War politics and post-Cold-War expectations; and (3) diversification of nuclear deterrence from the bilateral Cold War standoff to a bi-level global-regional model. This third factor was implicitly acknowledged in the 2010 Nuclear Posture Review Report, which numbers among its objectives Maintaining strategic deterrence and stability, and Strengthening regional deterrence and the assurance of our allies and partners."