The ‘Signalgate’ Group Chat May Be Evidence of a U.S. War Crime
Last week, the U.S. Defense Department’s inspector general announced a probe into Secretary of Defense Pete Hegseth’s use of a group chat on the commercial messaging app Signal, rather than secure government channels, to discuss sensitive operational plans in the runup to recent U.S. airstrikes against the Yemen-based Houthis. The probe, which was launched in response to a bipartisan request from the Senate Armed Services Committee, underscores the seriousness with which both Democratic and Republican lawmakers, if not the administration of U.S. President Donald Trump, are taking the national security implications of the incident, which risked the lives of military pilots undertaking the strikes.
Of more enduring concern, however, and largely lost in the ensuing controversy is what the Signal group chat revealed in terms of the Trump administration’s operational plans themselves: a strike on a civilian apartment building that reportedly killed 53 civilians in an effort to kill a single military commander, in a conflict of arguably little genuine military or political significance to U.S. national interests.
The strike itself, the reasoning behind it and the way in which senior Trump administration officials cheered as civilians died at best damages U.S. moral standing. But according to Amnesty International, the conversations that were laid bare in the Signal group chat also suggest the strike itself and the reasoning behind it may have violated the laws of armed conflict. If so, the Pentagon’s internal watchdogs have an opportunity to do more than just discuss communications strategy in their follow-up report—and congressional leaders should ask them to do so.
Leaving aside the propriety of discussing the strikes on Signal, the exposed group chat showcased uncertainty among U.S. political leadership about the military necessity of resorting to force at all against the Houthi rebel group in Yemen. Vice President JD Vance even indicated that he thought the strategy was inimical to U.S. national security goals.
Vance may have been right. As Benjamin Friedman and Rose Kelanic argued in a WPR briefing last week, airstrikes against the Houthis are not only unnecessary, given that the group is “little more than a nuisance in global economic terms,” but also ineffective, as the weapons it uses to attack ships are “hard to locate and destroy from the air but easy for them to replenish.” Moreover, as Sarah Philips points out, airstrikes that disproportionately harm Yemeni civilians compared to Houthi leaders, fighters and assets actually have the perverse effect of galvanizing and emboldening the group.
This matters in legal terms because the international law on targeting in armed conflict allows even minimal civilian casualties only in situations where the expected collateral damage is outweighed by genuine military necessity. Further, even if one could argue that there was a clear and present danger to U.S. national security interests to justify the overall attacks, and even if there were some evidence that airstrikes against a deeply embedded and dug-in militant group were militarily effective and therefore necessary, the collateral damage in this strike relative to the alleged military personnel targeted was excessive.
Under international law, the burden of proof is now on the U.S. military and civilian leadership to explain to the public why this strike did not in fact constitute a war crime.
Note that according to the Signal chat, U.S. drones targeted a single Houthi commander, and not while he was alone in a car or in a military installation but as he “walked into his girlfriend’s building.” That building housed numerous other civilians, 53 of whom—including five children—were killed, according to the Houthi leadership. Even if these numbers were somewhat inflated for public consumption, this is an extraordinary price to pay for a single dead commander in any conflict, much less one with little strategic benefit to the United States.
While some civilian harm is unavoidable in wars, the U.S. military has a long history of avoiding or minimizing it for both ethical and strategic reasons, and the ratio of acceptable casualties per high-value militant has generally been far lower that 53-to-1. In fact, that ratio was adjusted downward by the administration of former President Barack Obama from a high of approximately 30-to-1 during the early war on terror, saving a significant number of lives. While no specific ratio is set down in treaty law, as Amnesty International notes, states have an obligation to minimize civilian harm, which they must weigh against the military value of a target. That accounts for the efforts many states have made in recent years to expand civilian harm mitigation and prevention architecture within their militaries.
Yet it is entirely unclear at this time whether, in conducting the attacks in mid-March, the U.S. military took any of the precautions required under Article 57 of Additional Protocol 1 to the Geneva Conventions, and if so which. What is certain is that no part of the conversation on Signal, including the back and forth about the wisdom of the strikes, suggested that the participants had considered civilian harm mitigation at all. It is notable that no lawyer from the U.S. military’s legal branch—known as the Judge Advocate General Corps, or JAG Corps—was present in the chat. And given the Trump administration’s recent directives decentralizing strike authority and slashing civilian harm mitigation efforts, it is unclear whether the attacks had even been evaluated by JAG Corps lawyers as the targets were being selected.
The infamous cheering of the civilian deaths by senior defense officials with a series of emojis and patriotic slogans certainly suggested the opposite: Either they were demonstrations of what political scientist Bruce Cronin refers to as a reckless indifference to the likely presence of civilians in the building targeted; or worse, they reflected a willful intent to harm them as part of the campaign.
Consider that upon learning that the bombs had hit the building of the target’s girlfriend and that the building “had now collapsed,” Vance responded, “Excellent,” and the CIA director wrote, “A good start.” National security adviser Michael Waltz infamously cheered the killings with emojis of a fist, a U.S. flag and a flame. Little respect or concern was shown for the civilians who were at that moment burning alive, dying of shrapnel wounds from U.S. explosive devices, or crushed and suffocating under the rubble of the collapsed building.
Even had civilian life been weighed against military advantage in this case, the law on proportionality only applies to situations in which a target is already a legitimate military objective. But the residential building in question was not itself a legitimate military objective in the first place, but rather a civilian object. To be sure, civilian objects can become legitimate military objectives if they are used by militants as staging grounds for attacks. But this is not the case when a military commander simply walks into a civilian building in the course of his day-to-day business. In such a situation, while the commander may arguably be a target, an entire building cannot be.
And while the law on proportionality may be vague and subject to interpretation, the plain language of international treaty rules on targeting civilian objects are emphatically clear: Article 52 of the Additional Protocol to the Geneva Conventions states that “attacks shall be limited strictly to military objectives” and that “civilian objects shall not be the object of attack.” Additionally, according to Article 50, “the presence within the civilian population of individuals who do not come within the definition of civilians does not deprive the population of its civilian character.” Moreover, “in case of doubt whether an object which is normally dedicated to civilian purposes, such as a place of worship, a house or other dwelling or a school, is being used to make an effective contribution to military action, it shall be presumed not to be so used.”
In other words, under international law, the burden of proof is now on the U.S. military and civilian leadership to explain to the public why this strike did not in fact constitute a war crime. Congress should demand such an accounting, given that the International Committee of the Red Cross considers these rules customary law, and they have also been incorporated into U.S. military manuals.
In addition to investigating how the details of the attack ended up in a Signal chat, the Pentagon should be asked explain to the public how the targets were selected; whether the attack was approved by JAG lawyers before it was undertaken; what precautions were taken to ensure that civilians were not the intended or unintended targets of the attack; how the possibility of civilian harm was minimized; and how it was determined that the military necessity of this attack outweighed the easily foreseeable harm to scores of noncombatants.
Getting this right is important not just for the legitimacy of U.S. military efforts abroad, but also for public opinion at home. At Sarah Kreps has noted, U.S. citizens are highly sensitive to the idea of civilians being swept up in the damage caused by U.S. bombs abroad, whether those bombs are launched by U.S. personnel or by U.S. allies such as Israel.
To redeem itself after the Signalgate scandal, the Trump administration and Defense Department must do more than commit to using appropriate channels of communication moving forward. They must sustain the U.S. military’s ability to communicate in a professional and lawful manner as it makes life and death decisions affecting both U.S. service-members and civilians in other lands, while minimizing any harm resulting from those decisions. Congressional leaders should hold both the military and its civilian leadership accountable for doing so.
Charli Carpenter is a professor of political science and legal studies at University of Massachusetts-Amherst, specializing in human security and international law. She tweets at @charlicarpenter.