Raindrops Keep Falling On My Nuclear Umbrella

Pyongyang’s provocative and erratic behavior is starting to unnerve South Korea. “Many people are alarmed by the North’s recent provocative acts and as they learn of an extreme reign of terror within North Korea,” South Korean President Park Geun-hye said on May 15 — two days before U.S. Secretary of State John Kerry arrived in Seoul to show the United States’ “ironclad commitment” to South Korean security. In the last month, Pyongyang announced the successful test of a submarine-launched ballistic missile, reportedly executed its defense minister for disobedience to North Korean dictator Kim Jong Un, and fired shells near a sea border disputed between the two countries. South Korea and Japan, two of the most likely targets for North Korean violence, are U.S. allies and protected by its nuclear umbrella. But as Park’s comments imply, that may offer little comfort: U.S. extended deterrence is not curbing its ally’s fears.

Since the early days of the Cold War, the United States has promised to deter and retaliate against a nuclear attack on select allies in Europe and Asia — in other words, the United States extends to them the capabilities it fields to protect the American public from nuclear attack. In Asia, the U.S. nuclear umbrella is reserved for only its close allies Australia, Japan, and South Korea — as it should be. Promises of nuclear retaliation on behalf of others shouldn’t be made lightly. When the United States promises to defend allies against the greatest type of destruction imaginable — while at the same time upholding defense treaty commitments against non-nuclear attack — this should assure close allies of their security. This is good for the United States because an assured ally is less likely to launch fear-based preventive strikes against adversaries; also, an assured ally also has no need to pursue its own nuclear weapons arsenal. If U.S. extended deterrence commitments work as intended, the confidence they provide to friends is just as important as the caution they should induce in would-be adversaries, like North Korea.

But while U.S. extended deterrence commitments to Japan and South Korea are the ultimate promise, it is a promise for the least-likely situation. And meanwhile, whether because of political expediency or the low stakes involved, the United States has played a marginal role in dealing with the smaller threats these two countries face: for Japan, Chinese harassment in waters around contested islands in the East China Sea; and for South Korea, conventional attacks by North Korea. The result? By failing to adequately tackle small-scale challenges with or on behalf of Tokyo and Seoul, the United States has cast doubt about its nuclear umbrella for those two countries.

This in turn reflects an unstated paradox: the strongest form of U.S. commitment doesn’t address the much weaker quotidian challenges actually facing its allies. Consequently, Seoul and Tokyo look to Washington and see its credibility eroding. Frank Sinatra once sang that if he could make it in New York, he “could make it anywhere.” This logic, dubbed the “Sinatra test,” suggests that those who can survive a hard test can survive an easy one. But when it comes U.S. extended deterrence, allies see the opposite: if the United States can’t handle the small threats, then how can it handle the big ones, like nuclear attacks?

Consider what happened in 2010, when North Korea torpedoed the South Korean frigate Cheonan, killing 46 seamen, and then followed up that provocation in November of the same year by shelling the Yeonpyeong Islands, killing four South Koreans and injuring 19 others. Officials in Washington urged restraint, and prevented South Korean retaliation. The response was telling: Politicians in Seoul, in a move that signaled their doubt over the reliability of U.S. commitments, called for the redeployment of U.S. nuclear weapons on Korean soil (all U.S. nuclear weapons had been removed from South Korea in 1991). And because the United States is not planning to redeploy its nuclear weapons, several senior South Korean politicians have called for the country to develop their own bomb — concluding that if the U.S. nuclear umbrella couldn’t protect their country, they would have to rely on their own nuclear capability.

Consider also what’s happened over the last five years to Japan, a top U.S. ally. China has repeatedly confronted Japan over the Diaoyu islands Tokyo claims (and calls the Senkaku). Beijing has asserted its claims with novel and aggressive moves that fall just under the threshold for retaliation — using water cannons, fishing vessels, reconnaissance drones, and military ships nominally designated as Coast Guard vessels to harass Japanese vessels. And consider, for example, Japan’s response to the unarmed Chinese reconnaissance drones Beijing has frequently dispatched into contested airspace over the last few years. In each case, Japan alone has scrambled fighter aircraft or sent maritime vessels in response. The more Japan does alone, the more it doubts the strength of the partnership. The U.S. commitment to protect Japan against existential threats risks being eroded by its irrelevance in protecting Japan from the primary — though relatively small — danger it faces today. As Prime Minister Shinzo Abe bolsters Japan’s military, Japan’s departure from a long history of buck-passing its security burden to the United States only makes sense as a response to feeling more threatened and lacking confidence in U.S. reliability.

Of course, in these cases Japan and South Korea (not to mention much of the rest of the world) would have been discomfited if the United States threatened nuclear retaliation — and that illustrates the problem. Extended deterrence is a blunt instrument: good for some things, like deterring nuclear attack, but not for others, like deterring provocations or low-intensity conflict.

The United States has known this for a long time. One of the lessons of the Cold War was that nukes aren’t good for much — other than deterring other nukes. President Dwight Eisenhower’s doctrine of “massive retaliation” — promising nuclear retaliation against Soviet aggression — served many purposes, but non-nuclear deterrence or crisis management was not one of them. During the Korean War, U.S. nuclear threats failed to end the protracted conflict. In repeated crises with China in the 1950s, U.S. nuclear threats not only failed to prevent China from shelling and seizing Taiwanese-held islands, but boxed Washington into a path where some U.S. officials advocated nuclear attacks on China for the sake of strategically insignificant and militarily Taiwanese indefensible islands. These problems had to do with the credibility of proportionality: nobody believed big threats made over small issues. A nuclear umbrella, in other words, was too blunt an instrument to credibly wield as a coercive tool on the battlefield or as a means of preventing small-scale attacks against an ally.

Rather than drawing greater attention to the U.S. nuclear deterrent, the United States should devise long-term policies that help South Korea and Japan deal with North Korean provocations and Chinese coercion respectively — small-scale but significant problems. The United States should launch strategic consultations with South Korea and Japan to compare notes on global and regional trends (which includes small-scale coercion), and how they affect national threat perceptions, mission priorities, and military weapons investments. Though far less sexy than nukes, elevating cooperation with South Korea and Japan to strategy and policy planning consultations might go a long way toward shoring up their confidence.

None of this means that the United States should jettison its extended deterrence commitments — they reduce the arms racing that allies might otherwise engage in, and have alleviated the need for allies to launch preventive strikes out of misplaced fear or insecurity. U.S. extended deterrence has also helped reinforce the global norm against nuclear proliferation by helping maintain compliance to the Nuclear Nonproliferation Treaty; there would probably be more nuclear states in a world without U.S. extended deterrence commitments.

But extended deterrence commitments are likely to have diminishing returns over time. If allies can’t trust U.S. extended deterrence to deal with their needs today, why would they trust the U.S. ability to deal with their needs tomorrow, like protecting against a nuclear-armed North Korea?

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