New threat, new weapons

RESPONDING to Russia’s re-emergence as an adversary, the Pentagon’s first “nuclear posture review” since 2010, published on February 2nd, seeks to expand America’s nuclear options, but not the overall size of its arsenal.

The review largely confirms the wide-ranging modernisation programme that Barack Obama approved in exchange for Senate ratification of the New START strategic arms-control treaty with Russia. That programme, the Congressional Budget Office estimates, will cost $1.2 trillion over 30 years. It has its critics; the requirement for a new, stealthy air-launched cruise missile has been questioned, for instance.

But anyone who believes that America still needs a triad of reliable nuclear weapons—fired from land, sea and air—concedes that America’s ageing bombers, ballistic-missile submarines and ground-based intercontinental ballistic missiles must be replaced. There is also a strong case for improving the resilience of outdated nuclear command-and-control systems that are becoming highly vulnerable to cyber-hacking and new space weapons.

Where the new review parts company with its predecessor is in calling for the development of new, less powerful nuclear warheads (known as “low-yield”) to put on submarine-launched ballistic missiles and, in the longer term, a new submarine-launched nuclear cruise missile. The logic behind this move harks back to the cold war, when a strategy known as “flexible response” was conceived by the Kennedy administration.

The idea was that America should be able to respond in kind at any point on an escalation ladder that began with a conventional attack and ended with all-out nuclear war. Somewhere in the middle were tactical or battlefield nukes: relatively low-yield (around the explosive capacity of the bombs dropped on Hiroshima and Nagasaki), shorter-range missiles, artillery shells or gravity bombs that might be used against superior Soviet conventional forces if they were over-running NATO defences.

To an extent, the boot is now on the other foot. After the break-up of the Soviet Union, Russia’s conventional capabilities atrophied quickly. At the same time, America and its allies had shown in the first Gulf war, in 1991, what new precision deep-strike conventional weapons could do. While the West got rid of most of its tactical nuclear weapons, regarding them as no longer militarily necessary and potentially destabilising, Russia went in the opposite direction, seeing them as a way to offset the weakness of its conventional forces.

Although Russia has very substantially improved its conventional capabilities over the past decade, it has not weaned itself from “non-strategic” nuclear weapons. Rather, it has held on to about 2,000 such systems and modernised some of them (by contrast, America keeps just a few hundred low-yield gravity bombs in Europe).
After the annexation of Crimea in 2014, Vladimir Putin went out of his way to suggest that there were circumstances in which Russia might use such weapons. Russia says it would only resort to nuclear weapons if the homeland faced an existential threat. But that does not square with a doctrine it has developed known as “escalate to de-escalate”. This postulates that Russia would threaten the use of tactical nuclear weapons to bring to an end a military confrontation with the West it feared eventually losing.

Mr Putin appears to believe that under his leadership, Russia has a greater tolerance for risk than its NATO adversary. Such threats would thus be credible and effective. The nightmare scenario for NATO is that Russia might use its newly powerful conventional forces to make a lightning grab for territory in the Baltic region and then threaten to use low-yield nuclear weapons to dissuade any attempt to reverse its gains. If the only nuclear response America could make would be to launch an attack on Russia itself, thus risking nuclear Armageddon, it would be forced to back down.

Critics of America’s new nuclear policy argue that introducing more usable nuclear weapons will lower the threshold to using them, with potentially catastrophic consequences. Supporters argue that the opposite is the case. For nuclear deterrence to work, the possibility of a nuclear response must be credible. Paradoxically, introducing supposedly more usable nuclear weapons to the range of options thus makes nuclear war less rather than more likely.

Debates of this kind can never be resolved. But it would be wrong to associate the case the nuclear posture review soberly makes with Donald Trump’s bluster about wanting ever more powerful nuclear forces and the size of his nuclear button. The commander-in-chief’s impulsive personality and the scope for miscalculation over North Korea’s missile programme is far more worrying than a considered attempt to plug a gap in America’s nuclear arsenal.