Secretary of Defense Pete Hegseth, during a televised press briefing at the Pentagon on the Iran war on March 13, vowed this about America’s response to Iran’s ruling regime: “We will keep pushing, keep advancing. No quarter, no mercy for our enemies.”
These words in themselves could be a violation of both U.S. and international law.
Hegseth’s declaration of “no quarter” implicates a foundational prohibition under the law of war. These are the binding rules agreed to by states that seek to mitigate the horrors and bloodshed of conflict through pragmatic balancing of humanitarian and military considerations. The prohibition of the denial of quarter is a paradigmatic illustration of the law of war advancing both sets of considerations.
The law of war prohibits military leaders from the speech act of announcing “no quarter” alone.
Dating back to at least the Civil War, the denial of quarter has been forbidden. As articulated in the 1863 Lieber Code (Instructions for the Government of Armies of the United States in the Field, General Order No. 100), “It is against the usage of modern war to resolve, in hatred and revenge, to give no quarter. No body of troops has the right to declare that it will not give, and therefore will not expect, quarter.” (emphasis added) This rule would subsequently be incorporated into treaties to which the United States is a party, including in the regulations annexed to the 1907 Hague Convention IV, and as customary law binding on all states. Importantly, this law of war rule applies to air, land and sea warfare.
As reflected in the Lieber Code (and the Department of Defense’s own Law of War Manual), the ban on denial of quarter includes both: 1) a prohibition on conducting hostilities on the basis that legitimate offers of surrender by enemy personnel will not be accepted, but instead that there should be no survivors, and 2) a prohibition on simply declaring no quarter itself.
In other words, the law of war prohibits military leaders from the speech act of announcing “no quarter” alone.
The underlying logic of this rule should be obvious. The rule serves humanitarian purposes by prohibiting the murder of those no longer engaged in hostilities. And it serves a practical military purpose insofar as an enemy who believes surrender will not be accepted has nothing to lose by fighting to the death.
The prohibition on denying quarter is binding not only on states as a matter of international law, the denial of quarter is a war crime entailing individual liability for military leaders. For example, in the 1948 High Command Case at Nuremberg, a U.S. military tribunal tried senior German military officers for a range of war crimes, including “refusal of quarter.”
Denial of quarter is also a war crime under U.S. law. The War Crimes Act criminalizes violations of the following rule: “it is especially forbidden… [t]o declare that no quarter will be given.” Thus U.S. criminal law, like the international law of war, imposes individual liability for the speech act of declaring “no quarter” itself — regardless of whether the declaration is ever implemented. A declaration of no quarter by a military leader is not only an unlawful order (the subject of a now famous video message from a number of Democratic lawmakers), but one that a court would likely find to be manifestly or patently unlawful. This means that if military subordinates were to execute a directive of no quarter, they would have no viable defense of following superior orders. Once a television personality, Hegseth may have intended his bellicose rhetoric as a made-for-TV flourish. But his job description is different now. Despite his civilian attire, the Secretary of Defense is a military leader in the chain of command. Whether he appreciates it or not, his words alone have legal significance. A declaration of no quarter by a military leader is not only an unlawful order, but one that a court would likely find to be manifestly or patently unlawful. When leading lawyers in the George W. Bush administration sought to poke holes in the law of war, the resulting abuses caused reputational damage that the United States has yet to fully shake. Political and military leaders can and should stop history from repeating itself. In particular, Hegseth should publicly recant his “no quarter” comments and make crystal clear that U.S. service members must comply with the law of war, including by accepting surrender by the enemy, and that failure to do so will be vigorously prosecuted. Even if the current administration denigrates the law of war, lawmakers and 2028 hopefuls need to underscore that adherence is required and vow future accountability for violations. The U.S. itself agreed to be bound by law of war rules such as this one because it was in the humanitarian and military interests of the country. It remains very much in the U.S. national interests to comply with the law of war and promote compliance by other states.
Brian Finucane is a senior adviser with the U.S. Program at the International Crisis Group. 
