Defense In Depth
Why U.S. Security Depends on Alliances—Now More Than Ever
Few anticipated that 2016 would see such unprecedented missile and nuclear testing in North Korea, most recently its fifth and largest ever test, reportedly coming in at 10 kilotons. But none of this should have come as a surprise. Under Kim Jong Un, North Korea’s approach to developing its strategic forces is markedly different—more aggressive—than it was under his father or grandfather. The striking change puts the Korean Peninsula on a path to nuclear war unless the U.S.-South Korean alliance can adapt to the constraints of deterrence and defense against a second-tier nuclear-armed adversary.
Whereas Kim Jong Il’s North Korea conducted 18 missile tests during his 18-year reign, the last four years under Kim Jong Un have already seen 35 missile launches and three nuclear tests. In word and deed, Kim Jong Un has laid bare his intentions to mate nuclear warheads to long-range missiles, pursue a hydrogen-based nuclear bomb, and develop a submarine-launched ballistic missile capability, which has long been considered the gold standard of an assured retaliatory capacity. Gone are the days in which it is possible to speculate that North Korea’s nuclear weapons were mere symbols or bargaining chips, or that the threat of nuclear attack was “deeply hypothetical,” as a White House spokesperson during the George W. Bush administration once described it.
North Korea’s nuclear program is now more accelerated, less constrained, and more openly linked to its missile program than at any point in its history. Pyongyang is rushing to deploy a nuclear force that can ensure the regime’s survival by guaranteeing that any attempt to replace it or invade to North Korea leads to nuclear war. But Washington and Seoul are dealing with North Korea as if it were still the 1980s.
For a long time, North Korea’s foreign policy playbook has included recurring small, isolated, and deniable attacks against South Korean and U.S. targets. Historically, these attacks were backed by a willingness to wage conventional war if the alliance retaliated. These days, the stakes are even higher; those same kinds of attacks are backed by a willingness to risk nuclear war. In turn, the alliance’s policy playbook has historically involved nuclear threat-making, a willingness to impose regime change and unify the Korean Peninsula in the event of conflict, and continuous preparations to deploy large-scale military forces to make good on the threat.
Following this playbook, the alliance still routinely signals actions it is prepared to take against North Korea, from deploying nuclear-capable B-52 bombers, to dispatching aircraft carriers, to mobilizing hundreds of thousands of ground forces to invade and occupy Pyongyang. Yet going down either of those paths—U.S. nuclear first use or regime change—removes incentives for North Korean nuclear restraint in the event of conflict. By holding to its old ways, the alliance is unintentionally making any conflict more likely to go nuclear.
The Korean Peninsula’s best chance of avoiding a mushroom-cloud fate is by adapting to—not downplaying—the unique risks and requirements of deterrence against a second-tier nuclear-armed adversary. The alliance, and the United States in particular, must thread the eye of a tiny needle by fashioning a credible deterrent without igniting a nuclear war. Two steps toward adaptation are in order: reducing the role of nukes in alliance military signaling and planning and curbing the objectives and scope of conflicts that break out.
To refrain from nuclear signaling, the United States and South Korea will have to make several adjustments, including ending B-52 deployments to the peninsula, swapping nuclear-umbrella consultations with South Korea for gray-zone consultations, and creating greater distance from the prospect of U.S. nuclear first use.
The United States has a tradition of deploying B-52s—strategic bombers capable of carrying nuclear payloads—from Guam to the Korean Peninsula whenever it wishes to rattle its sabers at the North. The implication that Washington might be willing to use nuclear weapons gives North Korea incentive to place its nuclear weapons on alert, as Kim Jong Un ordered this past April. This was never really a problem in decades past, before North Korea had nearly deliverable nuclear weapons, but times have changed. And North Korean nukes or no, the alliance’s dramatic conventional superiority over North Korea moots any military need to resort to nuclear use. Moreover, as I explain in my book, Rival Reputations, there is no evidence that the B-52 flights have even changed North Korean perceptions of the alliance in a desirable way; the history of how the B-52 has been used in Korea—following incidents in which the alliance takes no real action in response to a North Korean attack—makes the flights more likely to signal fecklessness than resolve.
Nuclear signaling toward North Korea also takes subtler forms than the B-52 flight, such as publicly advertised nuclear-umbrella consultations between the United States and South Korea. Since the 1970s, the United States has pledged to extend its nuclear deterrence capability to select allies, including South Korea. Such efforts were ramped up in the wake of two North Korean strikes in 2010, when alliance officials established new consultation mechanisms to assure South Korea of the United States’ commitment and to coordinate their respective defense policies on North Korean nuclear weapons. As recently as February this year, the United States hosted what is now termed the Deterrence Strategy Committee with South Korea, which media statements characterized as burnishing U.S. nuclear forces to assure South Korea of their availability.
But since the United States neither needs nukes to destroy North Korea nor wishes to instigate North Korea’s nuclear trigger, consultations aimed at assuring South Korea of America’s commitment would be better spent on a more acute problem: working through when and how the United States would help South Korea respond to North Korean provocations, guerilla attacks, and limited-scope military campaigns. These are threats that live in what many policymakers now describe as a gray zone of conflict. They are concrete problems that South Korea actually faces, and whose occurrence gives rise to national angst about the credibility of the United States’ commitments. Following North Korea’s torpedo attack on a South Korean naval vessel in the Yellow Sea and an artillery attack against the South Korea–held Yeonpyeong Island in 2010, for example, South Korean officials openly questioned the viability of extended deterrence and introduced the idea of an independent South Korean nuclear weapons program. Since North Korean behavior—not simply the presence of nukes—is the primary concern, consultations with South Korea would be better if they focused on realistic problems rather than reifying unrealistic nuclear promises.
Further, the B-52 deployments and nuclear umbrella consultations are mere instruments made possible by a larger U.S. policy of withholding so-called negative security assurances from North Korea. The United States’ 2010 Nuclear Posture Review effectively promised all adherents of the Nuclear Nonproliferation Treaty (NPT) that it would not engage in nuclear use against them under any circumstances. As a declaratory policy, this amounted to a carefully crafted threat by omission. The United States does not extend its assurance of no first use to noncompliant states, meaning that nuclear strikes against North Korea remain possible as a matter of policy. Yet it is difficult to imagine a scenario in which a U.S. president sees either prudence or necessity in launching nuclear strikes—let alone preventive nuclear strikes—against North Korea, which makes the threat of doing so dubious.
There is of course no guarantee that restrictions on U.S. nuclear signaling would induce North Korean restraint in the event of conflict, but they would nudge North Korea (and the United States) away from reckless action by making nuclear weapons less salient to thinking about, planning for, and waging potential conflicts on the peninsula.
These measures may help reduce the nuclear temperature in the Korean Peninsula, but they do not address the need for a credible deterrent against the military adventurism of a nuclear-armed North Korea. The emerging situation presents a paradox. On the one hand, the alliance must demonstrate resolve by imposing unacceptable costs on North Korea for acts of aggression. At the same time, the alliance must do everything in its power to ensure that the regime in Pyongyang does not believe that the alliance seeks to destroy or replace it; those conditions would be a nuclear casus belli.
These seemingly contradictory requirements—of demonstrating resolve and conveying only limited aggressive intentions—can be reconciled by shoring up deterrence against low-level violence short of war and giving a new mandate to U.S. forces in Korea (USFK).
North Korea has a long history of unreciprocated small-scale violence—more than 1,300 incidents resulting in more than 1,600 casualties since 1961—which has convinced Pyongyang elites over time that there is no great risk in small, isolated, and deniable attacks. North Korea must be disabused of this notion by swift, concentrated retaliation in the event of future attacks; there is simply no other way to establish deterrence against transgressions short of war.
The role of USFK, meanwhile, must shift from its traditional role as tripwire—that is, a political symbol designed to ensure the dispatch of large-scale U.S. reinforcements in the event of war—to one capable of fighting and winning limited military campaigns on its own. Every year, USFK leads Key Resolve and Foal Eagle, major military exercises involving thousands of troops from throughout the region. USFK’s 28,500 troops are simply not designed to win a war on their own. But North Korea knows that large-scale flows of forces into South Korea are a prelude to regime change and attacks on Pyongyang, even if that is not what the alliance intends. Worse, North Korean diplomats warned the United States in 1994—a decade before the country had nuclear arms—that “we will not give you time to collect troops around Korea to attack us … if it is clear you are going to attack, then we will attack.” This threat should be taken at face value; if the regime believes it faces imminent demise, North Korean nuclear first use becomes much more likely. The implication for USFK is that it must prepare to achieve military objectives short of regime change and reunification without the support of massive reinforcements because to do otherwise is to risk unintentionally incentivizing a North Korean nuclear attack.
The greatest challenge for the next generation of U.S. and South Korean policymakers is not denuclearization or peaceful unification of the Korean Peninsula. These are noble visions, but they don’t match facts on the ground. Instead, the alliance must adapt to the evolving requirements of deterrence against a nuclear-armed adversary. This means demonstrating a greater willingness to meet violence with violence, marginalizing the role of U.S. nuclear weapons as much as possible, and self-limiting both the ends and the means of military conflict to avoid nuclear strikes based on misperceptions or unintended signals.
Former Secretary of Defense William Perry once wrote, “We must deal with North Korea as it is, not as we wish it to be.” With North Korea now an emergent threat, heeding his advice is more important than ever.