The Nukes We Need

Keir Lieber and Daryl Press, previously at Foreign Affairs, "Preserving the American Deterrent":

The success of nuclear deterrence may turn out to be its own undoing. Nuclear weapons helped keep the peace in Europe throughout the Cold War, preventing the bitter dispute from engulfing the continent in another catastrophic conflict. But after nearly 65 years without a major war or a nuclear attack, many prominent statesmen, scholars, and analysts have begun to take deterrence for granted. They are now calling for a major drawdown of the U.S. nuclear arsenal and a new commitment to pursue a world without these weapons.

Unfortunately, deterrence in the twenty-first century may be far more difficult for the United States than it was in the past, and having the right mix of nuclear capabilities to deal with the new challenges will be crucial. The United States leads a global network of alliances, a position that commits Washington to protecting countries all over the world. Many of its potential adversaries have acquired, or appear to be seeking, nuclear weapons. Unless the world's major disputes are resolved -- for example, on the Korean Peninsula, across the Taiwan Strait, and around the Persian Gulf -- or the U.S. military pulls back from these regions, the United States will sooner or later find itself embroiled in conventional wars with nuclear-armed adversaries.

Preventing escalation in those circumstances will be far more difficult than peacetime deterrence during the Cold War. In a conventional war, U.S. adversaries would have powerful incentives to brandish or use nuclear weapons because their lives, their families, and the survival of their regimes would be at stake. Therefore, as the United States considers the future of its nuclear arsenal, it should judge its force not against the relatively easy mission of peacetime deterrence but against the demanding mission of deterring escalation during a conventional conflict, when U.S. enemies are fighting for their lives.

Debating the future of the U.S. nuclear arsenal is critical now because the Obama administration has pledged to pursue steep cuts in the force and has launched a major review of U.S. nuclear policy. (The results will be reported to Congress in February 2010.) The administration's desire to shrink the U.S. arsenal is understandable. Although the force is only one-fourth the size it was when the Cold War ended, it still includes roughly 2,200 operational strategic warheads -- more than enough to retaliate against any conceivable nuclear attack. Furthermore, as we previously argued in these pages ("The Rise of U.S. Nuclear Primacy," March/April 2006 [1]), the current U.S. arsenal is vastly more capable than its Cold War predecessor, particularly in the area of "counterforce" -- the ability to destroy an adversary's nuclear weapons before they can be used.

Simply counting U.S. warheads or measuring Washington's counterforce capabilities will not, however, reveal what type of arsenal is needed for deterrence in the twenty-first century. The only way to determine that is to work through the grim logic of deterrence: to consider what actions will need to be deterred, what threats will need to be issued, and what capabilities will be needed to back up those threats.

The Obama administration is right that the United States can safely cut its nuclear arsenal, but it must pay careful attention to the capabilities it retains. During a war, if a desperate adversary were to use its nuclear force to try to coerce the United States -- for example, by threatening a U.S. ally or even by launching nuclear strikes against U.S. overseas bases -- an arsenal comprised solely of high-yield weapons would leave U.S. leaders with terrible retaliatory options. Destroying Pyongyang or Tehran in response to a limited strike would be vastly disproportionate, and doing so might trigger further nuclear attacks in return. A deterrent posture based on such a dubious threat would lack credibility.

Instead, a credible deterrent should give U.S. leaders a range of retaliatory options, including the ability to respond to nuclear attacks with either conventional or nuclear strikes, to retaliate with strikes against an enemy's nuclear forces rather than its cities, and to minimize casualties. The foundation for this flexible deterrent exists. The current U.S. arsenal includes a mix of accurate high- and low-yield warheads, offering a wide range of retaliatory options -- including the ability to launch precise, very low-casualty nuclear counterforce strikes. The United States must preserve that mix of capabilities -- especially the low-yield weapons -- as it cuts the size of its nuclear force.

More at the link.

VIDEO HAT TIP: William Jacobson.