The uncertain future of nuclear-arms control

Is nuclear-arms control unraveling? The 1987 Intermediate-Range Nuclear Forces Treaty (INF) has collapsed, the 2015 Iran nuclear deal is teetering, and North Korea has continued to expand its nuclear and ballistic-missile arsenal. Worse, it is unclear whether the United States will stick with the New START Treaty when it expires in 2021. That agreement limits (at 3,000) the number of strategic weapons Russia and the US have pointed at each other.

Fortunately, history offers some solace. During and after the Cold War, periods of arms-control breakdown were typically followed by phases of reconstruction. But reversing course is never easy. When it comes to bringing Russia, Iran and North Korea into compliance, experience shows that there are limits to what can be accomplished by leveraging alliances or pursuing military action. The remaining options are economic sanctions - which are effective only up to a point - and a further arms buildup, to induce renewed negotiations. To be sure, alliances historically have played an important role in nuclear non-proliferation. In Europe, the US-NATO nuclear umbrella prevented the bomb from spreading beyond Britain and France. When US intelligence agencies learned in the 1970s and 1980s that South Korea and Taiwan had secret nuclear-weapons programs, Washington threatened to withdraw its military and economic support, and the programs eventually were shut down.

But intra-alliance pressure has no role to play with respect to loners like North Korea, Russia and Iran. Despite China's military alliance and occasional summitry with North Korea, it has little influence over Kim Jong Un's nuclear ambitions. And while Britain, China, France, Germany and Russia may yet be able to pressure the US into renewing dialogue with Iran, their efforts have yielded no results so far. The use of force in nuclear-arms control has long been contemplated, but rarely pursued, because of the risks of retaliation or radiological fallout. When these risks are absent, military action becomes attractive. In 1981 and 2007, Israel bombed suspected Iraqi and Syrian nuclear reactors under construction, without blowback. In the 1991 Gulf War, the US Air Force struck Iraq's concealed enrichment plants with impunity. But this is not an option against Russia and North Korea today. A strike on Russia's contraband intermediate-range-missile arsenal or on North Korea's nuclear program could bring about the very scenario that arms control is supposed to prevent: nuclear war.

Iran is not Iraq or Syria. Either directly or through its various regional proxies, Iran could unleash a wave of retaliation against US interests, as demonstrated by the recent attack on Saudi Arabia's oil infrastructure. US policymakers would have to weigh this risk seriously Iran's situation is different. Fearing further Iranian enrichment activities, the US could, in theory, fashion a limited strike on Iran's nuclear facilities, on the assumption that the threat of further US action would deter an Iranian response. But Iran is not Iraq or Syria. Either directly or through its various regional proxies, Iran could unleash a wave of retaliation against US interests, as demonstrated by the recent attack on Saudi Arabia's oil infrastructure. US policymakers would have to weigh this risk seriously.

Barring effective alliance pressure or military action, another option historically has been to build up one's own arsenal. In the early 1960s, the US resumed nuclear-weapons tests in response to the Soviet Union's violation of the 1958 test moratorium, and this paved the way for the 1963 Partial Nuclear Test Ban Treaty. Similarly, the INF was agreed after the US deployed intermediate-range missiles in Europe in response to Moscow's introduction of such weapons. In each case, both sides concluded that tit-for-tat buildups had only increased their insecurity.

But in today's climate, using nuclear escalation to induce another round of arms-control negotiations would yield only mixed results. The US could try to intimidate the North Koreans by returning to South Korea the nuclear weapons that it removed in 1991.