George Perkovich is Director of the Nuclear Policy Program at the Carnegie Endowment for International Peace.

As the unipolar era ends, the pro-Western imagination somehow remembers the Cold War as halcyon days for extended deterrence. In fact, extended deterrence was always problematic. It is not much more so today.

Extended deterrence often is conflated with extended nuclear deterrence. The two are not the same. I assume we are here debating the life or demise of extended nuclear deterrence. In that case, the key question is, 'what are we expecting US nuclear security guarantees to deter?'

US allies naturally wish that American policies and weapons will deter a wide range of possible threats. In Eastern Europe today, this could include threats of Russian military intervention in territorial disputes (a la Georgia), or Russian energy blackmail, or cyber-attacks as Estonia experienced in 2007. 

In East Asia, American allies and friends worry over China's growing aggregate power and the possibility of being pushed around over economic issues, control over natural resources and disputed islands, policy toward North Korea, and the security of cyber networks. South Korea and Japan understandably also fear North Korean aggression of various sorts.

In evaluating deterrence of these threats (by whatever means) we must not ask the US to do for others what it has not been able to do for itself. The US was unable to deter Afghanistan from enabling al Qaeda to undertake the 9/11 attacks. It did not deter Saddam Hussein from invading Kuwait in 1990, nor coerce Saddam to abide by UN resolutions in the run up to the 2003 war. India's nuclear weapons did not deter Pakistan from the Kargil intervention in 1999. 

In short, nuclear-armed states have been unable to deter a number of very unwanted challenges to their security and those of their allies. What they have been able to deter, generally, is large-scale aggression that would threaten their own existence or those of their protectorates. In other words, nuclear weapons deter only those threats against which it is credible to use nuclear weapons.

In cases where the potential aggressor wields nuclear weapons, this means that the threat must be sufficiently grave for the deterrer to risk escalation to nuclear war, with the potential result of mutual suicide. It is not credible to take such mortal risks unless the alternative would also threaten one's existence or, in the case of allies, one's identity and viability as a great power. 

Therefore, extended nuclear deterrence should only be relevant against threats of such magnitude that the possible use of nuclear weapons to deter or defeat them would be proportionate. Against lesser threats, other means of deterrence must be relied upon. In East Asia today, this means, for example, that nuclear weapons should not be expected to deter potential Chinese efforts to occupy disputed islands in the South and East China seas, or to deter most probable forms of cyber disruption or political-economic bullying. Other means, including strengthened combined-allied conventional forces and operations, should be enhanced for these purposes.

The DPRK is a particularly troubling case. What scale and type of aggression by Pyongyang would credibly justify and call for US nuclear retaliation (including pre-emptively)? The US can destroy North Korea's military and economy, albeit at enormous costs not only to North Korea but also to South Korea. But the underlying challenge then (and now) is to replace the government in North Korea by one that is civilized to its own people and others. Nuclear weapons offer little to this end.

In the nuclear age, revisionist states, insurgents, and terrorists have learned to utilise asymmetric 'weapons' to fight more powerful nuclear-armed states. Nuclear weapons will remain for the foreseeable future in the background to deter existential-scale threats, but other means must occupy the foreground. Rather than wishing for nuclear weapons to do the job, or hand-wringing that they cannot, we should concentrate on developing credible strategies and capabilities to deter insidious new forms of aggression and subversion.

There is no material reason to think that US interest in moving gradually and multilaterally toward a world in which no one possesses nuclear weapons should undermine extended nuclear deterrence. The US is emphatically clear that, as long as anyone has nuclear weapons, and the nonproliferation regime is not extremely robust, the US will retain nuclear weapons and a state-of-the-art nuclear infrastructure. 

US interest in nuclear disarmament stems from the perception that a world without nuclear weapons would give it a greater advantage against others that might threaten it or its allies.  The others – particularly China, Russia and North Korea – recognize this! They see the Obama agenda as a means of strengthening the US advantage. Hence they (and Pakistan) are likely to impede nuclear disarmament. How does this weaken extended nuclear deterrence?           

It is easy to raise questions about the viability of extended nuclear deterrence in a vacuum, forgetting that nuclear deterrence comes with the real risk that the weapons will be used. Serious policy-making should focus on how to redress insecurities and deter and prevent war without the catastrophic risks of nuclear proliferation and use. The US is committed to leading in this direction. It would welcome similarly serious efforts by other influential states to address these underlying political-security challenges.


Photo courtesy of Wikipedia.

The Nuclear Reactions column is supported by the Nuclear Security Project of the Nuclear Threat Initiative, as part of a wider partnership between the NSP and the Lowy Institute.