Indo-Pacific Experts: We Must Prepare for Limited Nuclear Attack

The United States and its allies are insufficiently ready for conflicts that involve limited nuclear attacks (LNAs), according to a new study by Markus Garlauskas, director of the Indo-Pacific Security Initiative, Scowcroft Center for Strategy and Security, Atlantic Council, and several colleagues.

“When thinking about this problem of limited nuclear attack, until we are better prepared to deal with it, we are not going to be able to respond rationally to this sort of threat,” Garlauskas noted, speaking to reporters at a May 13 Defense Writers Group meeting in Washington, D.C. He was joined by Lauren Gilbert, deputy director of the Indo-Pacific Security Initiative, Scowcroft Center for Strategy and Security, Atlantic Council.  

LNAs are smaller, more targeted nuclear offenses, such as a strike against assets at sea or underwater, or high-altitude/atmospheric detonation, he said.

Usually, what comes to mind with nuclear warfare are the larger, devastating attacks. “A lot of people, particularly in the general public, they hear ‘nuclear’ and they think, ‘Well, the world is over,’” Gilbert explained. “And so, the amount of public panic that it causes has been seriously affecting decision-makers because they are having to respond to the general public.”

LNAs, meanwhile, are not what people think of when they think "nuclear." LNAs could impact one military base without affecting surrounding areas. A low-burst, low-yield warhead (such as a 1.5-kiloton warhead) could be employed, or a higher-yield warhead could be used for airbursts in low-population areas, for example.

“LNA, for the purposes of this study, is an adversary’s employment of nuclear weapons for lethal, destructive and/or electromagnetic effects on U.S. and/or allied personnel and assets, while remaining limited in effect due to some combination of scope, scale, damage and targets,” the report indicated.

Garlauskas, as principal investigator, and the group, prepared the report for the Defense Threat Reduction Agency as part of its strategic Trends Research Initiative.

The study, "Limited Nuclear Attack in East Asia: Preparing and Responding with Allies and Partners – Guardian Tiger III," was part three of the council’s greater Tiger Project that is examining war and deterrence in the Indo-Pacific.

The group spent the last year conceptualizing what limited nuclear attack would look like and the associated geopolitical considerations as part of a research and tabletop exercise.

The tabletop exercise focused on North Korea as the case study to illustrate the LNA challenge to the United States and its allies, the report clarified.

“Vastly outclassed by the United States and the Republic of Korea in non-nuclear military capability and economic power, North Korea relies heavily on the threat of nuclear escalation as part of its coercive diplomacy,” the study said.  

In particular, North Korea has the capability to conduct LNAs, in addition to having the intent, Garlauskas said.

“North Korea clearly has the capability,” he stated. “But also, our assessment is that they have the intent to use nuclear weapons, other than for an all-out purpose. The basic idea is that [LNAs] are limited in terms of scope, where they are not causing a huge amount of civilian casualties, and that is allowing you to create dilemmas, then, for how the U.S. and its allies would respond to this form of attack.”

Kim Jong Un, North Korea’s supreme leader, has also pursued changes to the nation's constitution that support the possible use of LNAs. Moreover, Kim does not think of LNAs just as last resort, Garlauskas noted.

“We have seen in their constitution the way they made changes to account for nuclear weapons,” he shared. “They are thinking about these things not necessarily just as a last resort. When you look at the conditions that they are talking about for nuclear weapons employment, these could be early in a conflict or potentially later in a conflict to stave off defeat, but not necessarily as a last-gasp risk.”

Kim, Garlauskas continued, has driven the development of capabilities “well-suited” to LNAs, including a new tactical warhead and a nuclear-capable underwater drone.

The study examined three of the country’s existing capabilities: the peanut, the disco ball and the olive, which despite the funny names pointing to the weapon’s shape or appearance, are believed to be quite effective.

The peanut is an apparent two-stage thermonuclear device, suitable for airburst attacks aimed at electromagnetic pulse effects with a high-level detonation, the study noted.

The disco ball is reportedly a single-stage implosion device with a 20-kiloton yield, the report said. The olive, meanwhile, is a lower-yield fission device, less than 20 inches in diameter. North Korea calls it the Hwasan-31 or the Volcano-31, and it is considered as a tactical warhead that can fit onto eight different delivery systems. Kim claims that they have tested both the peanut and the disco ball.

The complication is the United States’ reaction to a possible LNA—given the ambiguity of thought as to whether an LNA would constitute a nuclear attack.

“One thing that we noticed going across the three tabletop exercises was the sheer level of biases that was built in, particularly for the U.S. participants on that there would not be a nuclear use,” Gilbert stated. “If there was a nuclear use, it was ‘just demonstrative,’ and the feeling was we cannot use a nuke back, or that will further escalation. And so, there was a lot of hesitation each time in each exercise.”

The advantage to North Korea or another adversary developing LNAs is this misperception and indecisiveness on how to react to LNAs.

“Widespread public misconceptions regarding nuclear weapons, particularly exaggerated fatalism about nuclear escalation and nuclear effects, coupled with difficulty in rapidly characterizing the effects of a given LNA post-strike, complicate efforts to foster resilience,” the report stated. “Our analysis across a broad range of nuclear experts as well as defense and international interagency practitioners suggests that the psychological and alliance effects of an LNA would far eclipse direct kinetic and radiological damage. This disproportionality underscores the need to proactively cultivate and bolster national resilience against these often undermined, underestimated, yet potentially catastrophic, non-kinetic consequences.”

LNAs by North Korea would be particularly challenging, given the geopolitics of the region.

“On the Korean peninsula, you have three nuclear-armed adversary countries very close geographically together,” Garlauskas said. “You are literally talking about North Korea on the doorstep of both China and Russia. And so, I think that is the first lesson from all three exercises. You have to consider how the adversaries are mutually supporting [that country] and how the others will see your response to limited nuclear attack.”

As such, the Indo-Pacific experts advised leaders to develop “a deeper and broader understanding” of the risks of LNA to ensure effective preparation. This means creating tailored products for leadership and leveraging existing training, education and exercises that involve LNA-related scenarios and mitigation steps.

The study recommended that leaders “establish and employ new and restored unclassified education and training curricula on LNA effects,” including educational materials. Working with allies, the United States should create a common context of LNA, the report stated.

In addition, the military and government should identify and mitigate constraints that prevent the United States and allies from preparing for LNAs. The leaders should also engage with East Asian countries to enable capacity-building to assess and manage in those countries.

“[We should] assess and execute posture/capability adjustments (nuclear and non-nuclear strike options and missile defense) to ensure resilience and more flexible military response options,” the report stated.

Lastly, Garlauskus emphasized that preparing for LNAs is not a trade-off.

“Until we are better prepared, it is irrational to expect rational reactions to a limited nuclear attack,” Garlauskas stated in the study.