Does law—international jus ad bellum or domestic war powers—substantially influence U.S. threats of force against North Korea? Does law enhance or degrade deterrence of North Korean provocations? Does it help or hinder efforts to coerce North Korea toward concessions?

These questions are rarely asked, but they should be. Here’s why.

There is vigorous debate on Lawfare and other blogs among international legal scholars and practitioners about whether a “bloody nose” strategy—a limited military strike in response to a North Korean provocation—or a more significant attack by the United States against North Korea’s nuclear weapon capabilities would be legal under international law. President Trump’s taunts of North Korean leader Kim Jong Un, his extreme rhetorical threats like “fire and fury,” and media reports about military planning have also inflamed long-running debates about the president’s unilateral constitutional power to initiate military hostilities.

These debates have caused me to revisit my own thinking—so far without clear answers, though—on the president’s constitutional power to threaten force (see here and here) and the relationship between international law on force and strategies of threatened force (see here at pp. 184-86).

Both the international and domestic law debates involve competing risks, at least implicitly. Some advocates stress that the law should be sufficiently permissive and flexible to allow the United States to address militarily the North Korean menace (or cases involving other nuclear proliferators), while others stress that it should be sufficiently constraining and rigid to help prevent unnecessary and catastrophic war. Here in the United States, all sides of these debates generally agree that the law should accommodate the nation’s minimum, absolute security need and it should promote international peace and stability. But advocates often disagree about what legal formula regarding resort to military force can best achieve and balance those objectives. And those who completely reject any such inquiry as injecting too much policy and power politics into law are living in a fantasy world.

Missing altogether from this legal discussion is the importance of threatened force. Inter-state wars are (thankfully) pretty rare, but the United States wields threats of force and war all the time. We deter. We coerce. We reassure allies—or don’t. We have vast military forces available for war on the Korean Peninsula, and we hope we never have to use them for war, but in the meantime we exercise them, we alter their alert status, we make demonstrative shows of them, and so on.

Threats of force may prevent war, such as by deterring North Korean aggression or moving it toward the bargaining table. Threats of war may inadvertently cause North Korea to respond with its own threats or speed its nuclear weapon program development. Or threats may result in miscalculation and inadvertent escalation. Meanwhile, threats lacking credibility may invite more hostility or cause allies to hedge.

Threats of force are, in other words, constant grist for security strategy. Although they are the focus of vast political science and other scholarship, however, they are rarely of much interest to lawyers (I speculate about why there is this disciplinary gap here (pp. 1653-62) and here (pp. 184-85)). At least since Thucydides, for example, theorists of international conflict have focused on the “security dilemma,” or the problem that in taking steps to protect their own security, states create insecurity among others. Contemporary international relationship scholarship devotes a lot of attention to signaling and the ways in which threats of force might be made more or less credible, or more or less prone to misperception.

Notably, the role of law doesn’t appear much—if at all—in these discussions of threats. A rare example from legal scholarship is here, but try finding “international law” or “constitution” in the index of many international relations books about deterrence or the footnotes of security studies articles about military threat strategies.

If war breaks out with North Korea, prior threats will have played a role in that catastrophic outcome. If the crisis is resolved peacefully, threats will likely have been instrumental, too.

So I encourage those who think that law—whether domestic law of presidential war powers or international law regulating resort to force—is relevant to this outcome to consider questions such as:

Would a more flexible, permissive interpretation of anticipatory self-defense doctrine enhance the credibility of U.S. threats in ways that might help resolve crises like North Korea peacefully, or incentivize behaviors by threatened states that make escalation more likely?

It is often asserted that expansive, unilateral presidential powers to use force are important to the credibility of threats. Is that assumption valid, or should it be revisited in light of history and new understandings of the dynamics of threats (such as those described here)?

Is the legality of military strikes important to domestic public support or to allied and coalition support, and therefore important to the credibility of threats?

When force is used, does its justification or repudiation under international law expand or constrain subsequent options, including making future threats more or less credible?

Thomas Schelling decades ago posited the importance of “focal points”—or “each [side’s] expectation of what the other expects [it] to expect to be expected to do”—to international negotiations in the shadow of threats. Does international law regarding force serve as or contribute to such “focal points”?

All of this may sound unnecessarily academic to many lawyers. I'd argue, to the contrary: if law and its practical value only pick up the story when force is actually used, rather than much earlier and constantly when it is threatened, then law’s effects on war and peace are actually much less significant than many lawyers suppose.