De nouvelles propositions suggèrent qu'il n'y a aucune étape dans l'escalade à laquelle les États-Unis ne seraient pas en mesure de répondre réciproquement.
The proposal of new, low-yield warheads seeks to convince adversaries that there is no step in the escalation ladder that the US would not be able to answer reciprocally.
A preliminary version of the yet-to-be confirmed American Nuclear Posture Review (NPR) has drawn attention for its proposals to develop new, lower-yield nuclear weapons and new delivery means, along with a lower proposed threshold for use.
The preliminary document was heavily criticised by former officials from the Obama administration as well as the press, who argued that it shows that the Trump administration believes that a nuclear war can be won at an ‘acceptable’ cost.
But much of that criticism derives from the increasing polarisation of American political debate and the general rejection of Donald Trump as a president. In terms of the substance of the NPR, some of these critiques are overstated.
On delivery means, the proposals to develop replacements for the Ohio-class submarine, the Trident missile and the B-52 bomber were all agreed during the Obama administration. But the new NPR also includes proposals to replace the land-based Minuteman ICBM – ending the debate on whether or not to eliminate that wing of the nuclear triad – and to develop a new air-launched cruise missile to be deployed on the new bomber.
All of the delivery means to be replaced were inherited from the cold war and needed to be phased out sooner or later, regardless of the president in charge. The same is true for the proposed updates to the nuclear forces’ command and communication facilities and early warning sensors. No modern telephone company would run on 1980s equipment, so why should the American nuclear forces?
But then there are other, more controversial, proposals in the NPR, like developing new “low yield” warheads. Warheads, like delivery means, age and need to be replaced. Their components are corrosive and highly radioactive, placing stress on key components such as conventional explosives, fuses, electronics, and isolating layers between different materials of the nuclear core. Life extension programmes were initiated during the Obama administration. But the older the warheads, the more expensive life extension becomes and, at a certain point, producing a new warhead is within a similar range of cost. But why a low yield warhead?
Discussions about low yield warheads began in the 1970s. They did not come to fruition during the Cold War, partly because critics argued that they would lower the nuclear threshold, make a nuclear war appear to be containable, and hence seduce leaders into nuclear escalation.
The counter-argument is that a full-blown nuclear attack may not be credible in some situations, thus blunting the deterrence effect of a nuclear arsenal. But the nuclear posture of the Cold War era was designed with retaliation to a massive assault by the Warsaw Pact in mind, which would have been difficult to contain anyway. Hence low-yield “enhanced-radiation” weapons were never deployed to Europe.
But political circumstances – and Western societies - have changed since then. The post-Czernobyl, post-Fukushima, post-Cold War American, European, South-Korean, and Japanese societies have very different attitudes to what level of nuclear warfare they could tolerate.
Today, a ‘first strike’ of nuclear weapons – although still officially possible within US nuclear doctrine – seems very unlikely. Even nuclear retaliation is now almost unthinkable for the public. This has not gone unnoticed in Russia.
In the Zapad military exercises of 2009, 2013, and to some extent 2017, Russia rehearsed the use of limited low-yield nuclear strikes to intimidate the West into accepting Russian territorial gains. The exercises imply Russian expectations that Western societies – which struggle even to tolerate nuclear power plants - would back down rather than retaliate with full-scale nuclear weapons to such an attack.
The NPR seeks to convince Russia otherwise. Low-yield-weapons can minimise residual radiation as much as possible (nuclear weapons however will never be entirely “clean”), making them much more usable in response to such an attack by Moscow.
That does not necessarily make nuclear war more likely or imply that the US is confident a nuclear war could be contained. Rather, it aims to demonstrate to potential aggressors that there is no step in the escalation ladder the West would not be able to answer reciprocally, thus deterring a nuclear attack against the West.
Despite some suggestions to the contrary, the NPR does not indicate a preference for nuclear escalation, nor does it de-emphasise non-nuclear deterrence. In fact, it emphasises that the US is willing to engage in arms control negotiations on non-strategic nuclear weapons and, in concert with other nuclear powers, abolish this category of weapons entirely.
That would indeed be desirable. But it is unrealistic to expect Russia and China to sacrifice their large arsenals of modern non-strategic warheads if American would only lose a few old weapons whose operational value is questionable. In this sense, modernising the US nuclear arsenal could eventually assist the cause of multilateral nuclear disarmament.
However, while critiques of low-yield weapons are arguably misguided, there are other elements of the NPR that deserve criticism. Arming intercontinental-range submarine-launched ballistic missiles with sub-strategic warheads is not a good option in terms of crisis stability. Adversaries would not be able to distinguish the different warheads while travelling through space. Hence a limited attack would look like a full-scale attack, and likely trigger full-scale retaliation.
The doctrine also continues to be deliberately ambiguous on the possibility of a first use of nuclear weapons by the United States, leaving open the possibility of first use in response to a “massive non-nuclear attack” putting US or allied populations, infrastructure, or nuclear capabilities at risk. In fact the report frequently stresses this ambiguity. This is unhelpful. The United States can retaliate with a wide range of non-nuclear weapons to almost any contingency. Condoning a nuclear response to a non-nuclear attack might antagonise allies more than it deters adversaries.
From a European perspective, the clear commitment to NATO and European deterrence is reassuring, especially given Trump’s past wavering on the issue. However, the re-introduction of sea-launched cruise missiles as the primary non-strategic delivery means would reduce US dependence on European bases and dual-capable aircraft, and thus reduce European influence over US nuclear planning.
But many of Europe’s dual-capable aircraft need to be replaced as well. That provides an opportunity to reach out to Washington with Europe’s own ideas. The idea of dual-capable air-launched munitions (like the existing Taurus or Storm Shadow cruise missiles) built around an American nuclear component would offer increased range, flexibility and survivability to the European component. The more valuable the European contribution, the more Washington will be willing to listen to Europe in its nuclear planning.
This is an opportunity Europe should grasp. Whether one likes Trump or not, in the face of a resurgent Russia there is no substitute for US nuclear deterrence in the foreseeable future. Europe should take care to preserve its influence over this critical aspect of its security.