As Vice President Biden’s speech and an article in the NYT are emphasizing, a conventional deterrent capability is going to form a vital part of the President’s post-nuclear strategy. This is interesting, firstly because it demonstrates the President’s serious intention to put the US on the path to zero nuclear weapons, and secondly because it demonstrates a belief in the efficacy of non-nuclear arms. I find both ideas highly unlikely, if not dangerous, but for now, let us examine the second.
Thomas Schelling, in Arms and Influence, identified a distinction between “the power to hurt” and the power to seize territory forcibly, the latter being a means to military victory enabling the infliction of pain. Despite the “war is hell” strategies of Sherman or the “total war” strategies of embargo and strategic bombing in WWII, the use of pure violence could not precede military victory until the development and use of the atomic bombs. This distinction only sharpened with the development of jet bombers, missiles, and submarines as nuclear delivery platforms. The unique ability of nuclear weapons to deter is the ability of just a single warhead to deliver, within hours or minutes, total devastation of even the most advanced conventional weapons or inaccessible enemy cities.
Can conventional weapons accomplish as much? Biden speaks of missile shields and “conventional warheads with worldwide reach,” a reference to “Prompt Global Strike.” The basic idea is a Trident or other ballistic missile with tungsten “Rods from God” that will impact at hypersonic speeds, obliterating hardened bunkers or a 3000 sq. ft. area. This sounds impressive, except its launch looks completely indistinguishable from a nuclear weapon, so launching one would not allow the US a 30 minute strike capability without provoking nuclear war. In the future, the use of a hypersonic, air-launched cruise missile might overcome this flaw, leaving the US a quick, relatively sanitary way to evaporate targets of interest and opportunity. This vision of the future is convenient but flawed.
To be blunt: the ugly, apocalyptic horror of a nuclear strike is an inevitable, if not advantageous aspect of the weapon. The ability of the nuclear weapons to inflict total violence on cities is what subjugated Imperial Japan and deterred the superpowers from employing them against each other. Since the US cannot guarantee the destruction of an enemy capital or major city with these new conventional weapons, they will not have the same deterrent power as a nuclear weapon, especially vis-a-vis a nuclear state. For one, the US will lack the ability to conventionally decapitate enemy leadership. The inability of our intelligence to pinpoint Saddam, not of our strategic bombers to destroy his bunkers, was the main problem in killing him in 1991 and 2003. Cold war strategists just needed to know what cities the Premier might be in to launch a strike with a high probability of killing him and most of the Party leadership. With nuclear weapons, entire countries could be laid waste in minutes or hours, with slim chance of survival for political-military leadership or infrastructure. Nuclear weapons were effective strategic deterrents because they were destructive. Precision weapons cannot fill that role.
It seems unlikely that Prompt Global Strike could even destroy large contingents of conventional forces more effectively than nuclear weapons. A relatively dispersed fleet or armored division would require multiple conventional warheads, as opposed to one nuclear warhead, to eliminate. The possibility of nuclear weapons to create impassable or unusable territory was another advantage. These advantages matter less today, but they are still beyond PGS. But we could not have the same confidence conventional arms would destroy enemy nuclear weapons before they launch, an important criteria for replacing nuclear arms.
Nuclear weapons prevented war because they made it too horrible for most politicians to contemplate. Embracing hypersonic conventional weapons seems to me an interesting option if America wishes to have a “splendid first strike” capability against small numbers of high-value targets (people, infrastructure, WMDs) in the DPRK, Iran, or the NWFP, though the intelligence necessary for this is probably understated. Until they can match the raw brutality of nuclear weapons, however, they probably cannot replace them as our unimpeachable deterrent, leaving a totally nuclear free US an unsafe and unrealistic dream.