The Laws of War: How the US Follows (and Doesn’t Follow) International Rules

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War is chaos, but it’s also one of the most strictly regulated human activities. For the United States, a superpower with troops from Eastern Europe to Syria, the Law of Armed Conflict (LOAC) is a daily operational reality that dictates which targets can be struck, which weapons can be used, and how soldiers must behave.

This guide explains how the U.S. government wields power in your name, and answers a fundamental question: In an era of great power competition and asymmetric warfare, is the United States truly bound by the laws of war?

In This Article

• The article explains the foundations of the laws of war, emphasizing that the U.S. played a major early role through the 1863 Lieber Code and later adoption of the Geneva Conventions.
• It outlines the core legal principles guiding U.S. conduct in conflict: distinction, proportionality, military necessity, and humanity.
• The U.S. is described as selectively adopting international treaties—ratifying the 1949 Geneva Conventions but not the 1977 Additional Protocols—while relying heavily on customary international law and domestic military doctrine.
• Enforcement mechanisms are said to operate largely within the U.S. military justice system rather than through international courts.
• The article portrays the U.S. as generally compliant with the laws of war, though acknowledging areas of debate and evolving challenges like cyber and AI-enabled warfare.

So What?

• Understanding how the U.S. interprets and applies the laws of war matters because it shapes global expectations, coalition practices, and civilian protection during modern conflicts.
• The U.S. remains a major military actor; its choices influence the evolution of international humanitarian norms.
• As new technologies emerge, U.S. interpretations may set precedents—positive or negative—for future warfare.

America Invented Modern War Rules

Contrary to perception, international law isn’t a foreign imposition. The modern codification of war rules is largely an American invention, born from the nation’s bloodiest conflict.

The Lieber Code

During the Civil War, President Lincoln faced a dilemma: how to fight a brutal war against rebels without descending into savagery that would make reconciliation impossible.

The solution was General Orders No. 100, signed in 1863. Known as the Lieber Code, named after its drafter Francis Lieber, this document was the first modern codification of war laws issued to a field army.

The Code established principles that remain central today. It explicitly stated that “men who take up arms against one another in public war do not cease on this account to be moral beings, responsible to one another and to God.” This was radical: the state’s right to injure its enemy was not absolute but limited by humanity.

The Code inspired European powers to adopt similar rules, eventually leading to the Hague Conventions of 1899 and 1907.

The American Red Cross Connection

The American Red Cross, founded by Clara Barton after her Civil War experiences, further cemented the U.S. role in developing International Humanitarian Law (IHL). Barton advocated for U.S. ratification of the first Geneva Convention.

This history underscores a critical point: the U.S. military’s adherence to LOAC is not merely about avoiding international sanctions. As the DoD Law of War Manual states, it is “part of who we are.” From George Washington’s orders to treat prisoners with humanity to the prosecution of American soldiers for war crimes in the Philippines and Vietnam, there’s a continuous thread of legal restraint in American military history.

What Treaties Bind the US?

The question “Is the US bound?” requires navigating complex legal obligations. The United States is simultaneously a primary architect of the global legal system and its most significant skeptic.

The Geneva Conventions: The Foundation

The absolute baseline for U.S. operations is the four Geneva Conventions of 1949. Negotiated after World War II and the Holocaust, these treaties serve as the “constitution” of international humanitarian law. The United States has ratified all four, making them “the supreme Law of the Land” under the U.S. Constitution.

These conventions are non-reciprocal. This is vital: the U.S. is bound to treat an enemy prisoner humanely even if the enemy tortures American prisoners. The obligation is to the human being, not the opposing government.

The Additional Protocols: Where the US Diverges

Where the U.S. position becomes controversial is regarding the Additional Protocols of 1977. These protocols were designed to update the 1949 Conventions for modern warfare, specifically insurgencies and civil wars.

Additional Protocol I (International Conflicts): The United States signed this treaty but never ratified it. The rejection solidified during the Reagan Administration. The primary objection lies in Article 1(4), which elevates “wars of national liberation” to international armed conflict status. The U.S. argued that this politicized humanitarian law by granting Prisoner of War status to irregular guerrilla fighters simply because they claimed to be fighting colonial domination.

President Reagan famously decried this as a “collectivist apology for attacks on non-combatants.”

However, the U.S. acknowledges that most of Additional Protocol I reflects Customary International Law. This means that while the U.S. isn’t a party to the treaty, it considers itself bound by specific rules within it, such as the definition of a military objective and the prohibition on indiscriminate attacks, because these rules have become accepted state practice.

Additional Protocol II (Non-International Conflicts): Similarly, the U.S. has not ratified Additional Protocol II, which governs civil wars. However, President Reagan actually recommended its ratification in 1987, arguing it contained “reasonable standards.” While the Senate never consented, U.S. policy is to apply the core principles to all conflicts.

Customary International Law

Beyond written treaties, the U.S. is bound by Customary International Law. This consists of rules that states follow out of a sense of legal obligation.

For example, the U.S. is not a party to the 1954 Hague Convention on Cultural Property, yet U.S. targeting protocols strictly avoid hitting mosques, museums, and historic sites unless they’re being used for military purposes. This adherence is driven by recognition that protecting cultural heritage is now a customary norm binding on all nations.

The Four Principles: How Commanders Make Decisions

In combat, whether a drone operator in Nevada tracking a target in Somalia or an infantry commander in Damascus, decisions are guided by four interdependent legal principles. These aren’t abstract ideals but operational checklists drilled into U.S. personnel.

1. Military Necessity

This principle authorizes the use of force required to compel the enemy’s submission. It’s the “sword” of LOAC. The U.S. definition permits “any amount and kind of force… with the least possible expenditure of time, life, and money,” provided it’s not otherwise prohibited.

Implication: If a factory produces tank parts, destroying it is a military necessity. If a civilian house is being used as a sniper nest, destroying it becomes necessary.

Limitation: Necessity doesn’t justify prohibited acts. A commander cannot torture a prisoner to get intelligence, even if that intelligence is “necessary” to save lives.

2. Humanity

Humanity is the “shield.” It forbids the infliction of suffering, injury, or destruction that’s not necessary to accomplish a legitimate military purpose. This principle drives prohibitions on weapons designed to cause superfluous injury (like glass-filled ammunition) and the mandate to treat detainees with dignity.

In the U.S. view, humanity and necessity aren’t opposites; they’re counterweights that keep warfare from devolving into extermination.

3. Distinction

Distinction is the most critical and difficult principle in modern asymmetric warfare. It requires parties to distinguish at all times between:

• Combatants (who can be attacked)
• Civilians (who cannot be attacked)
• Military Objectives (which can be destroyed)
• Civilian Objects (which are protected)

The Challenge of “Direct Participation”:

U.S. policy states that civilians lose their protection “for such time as they take a direct part in hostilities.”

Example: A farmer picking crops is a civilian (protected). If that farmer picks up a radio to spot targets for an artillery strike, he’s directly participating and becomes a lawful target. If he drops the radio and goes back to farming, he regains protection (though he can be arrested for his past acts).

U.S. Nuance: The U.S. takes a broader view of “direct participation” than some allies or the International Committee of the Red Cross. The U.S. argues that members of organized armed groups (like ISIS or Al-Shabaab) have a “continuous combat function” and are targetable at all times, not just when holding a weapon.

4. Proportionality

Proportionality is the most misunderstood principle. It doesn’t mean the force used must be equal to the threat (you don’t have to use a rifle to fight a rifle).

The Legal Definition: An attack is prohibited if the expected incidental loss of civilian life or damage to civilian objects would be excessive in relation to the concrete and direct military advantage anticipated.

The Equation: (Civilian Harm) < (Military Advantage)

Operational Reality: If a high-value terrorist leader is in a building, a commander must estimate how many civilians might be killed in the strike. If the target is a low-level foot soldier, killing 10 civilians is likely disproportionate (illegal). If the target is a general planning a nuclear attack, killing 10 civilians might be deemed proportional (legal, though tragic).

U.S. Doctrine: The U.S. Army notes that this balancing can be done against “overall campaign objectives,” not just the tactical value of the specific target. This allows for a wider aperture in justifying strikes that advance broad strategic goals.

How the US Enforces These Rules

While international courts grab headlines, the primary mechanism for enforcing war laws on U.S. personnel is domestic. The U.S. maintains a robust, self-contained legal system designed to punish violations without external interference.

The Uniform Code of Military Justice (UCMJ)

Every U.S. service member is subject to the UCMJ. While the code doesn’t have a single article titled “War Crimes,” it incorporates these offenses through other punitive articles.

• Article 118 (Murder) & Article 119 (Manslaughter): Used to prosecute unlawful killings of non-combatants or prisoners
• Article 128 (Assault) & Article 93 (Cruelty and Maltreatment): Used to prosecute abuse of detainees
• Article 92 (Failure to Obey an Order): Since compliance with the Law of War is a standing general order, any violation is automatically a violation of Article 92

Recent Enforcement Actions (2024-2025):

The military justice system remains active.

• United States v. Love (July 12, 2024): At Fort Carson, SPC James A. Love was convicted of desertion and willfully disobeying a superior commissioned officer. While not a “war crime,” the conviction reinforces the chain of command’s integrity, which is essential for enforcing LOAC.
• United States v. Michaels (July 2, 2025): MSG John A. Michaels was convicted at a special court-martial for attempted patronizing of a prostitute and failure to obey a general regulation.

The War Crimes Act of 1996

For situations where the UCMJ might not apply (private military contractors or former soldiers), the War Crimes Act of 1996 provides federal jurisdiction.

Scope: It applies if the victim or the perpetrator is a U.S. national or member of the Armed Forces.

Offenses: It criminalizes “grave breaches” of the Geneva Conventions (torture, willful killing) and violations of Common Article 3.

Penalty: Life imprisonment or death if the victim dies.

Permanence: Crucially, there’s no statute of limitations for grave breaches. A war crime committed in 2025 can be prosecuted in 2055.

The Leahy Laws: Policing Partners

The U.S. also polices its allies through the Leahy Laws. These statutes prohibit the Departments of State and Defense from providing military assistance to any foreign security unit if there’s “credible information” that the unit has committed a “gross violation of human rights.”

Mechanism: If a specific battalion of a partner nation executes prisoners, the U.S. must cut off aid to that specific battalion until the partner government takes effective steps to bring the responsible members to justice.

2025 Application: This law became a central point of contention regarding U.S. aid to Israel and the new Syrian authorities in 2025.

The US vs. The International Criminal Court (2024-2025)

The most explosive development in the U.S. relationship with international law has been the open conflict with the International Criminal Court (ICC). The U.S. isn’t a party to the Rome Statute (which created the ICC), citing concerns that the court lacks sufficient checks and balances and could be used for politically motivated prosecutions.

The Arrest Warrants

In November 2024, the ICC issued arrest warrants for Israeli Prime Minister Benjamin Netanyahu and former Defense Minister Yoav Gallant, alongside Hamas leaders, alleging war crimes and crimes against humanity in Gaza.

The U.S. position was unequivocal: since Israel (like the U.S.) isn’t a party to the Rome Statute, the ICC’s assertion of jurisdiction was legally invalid and politically dangerous.

Executive Order 14203

On February 6, 2025, President Trump signed Executive Order 14203, titled “Imposing Sanctions on the International Criminal Court.” The language was stark, framing the ICC’s actions as an assault on national sovereignty.

Key Provisions:

• Asset Freezes: Any property belonging to designated ICC officials within U.S. jurisdiction is blocked
• Visa Bans: Designated ICC officials and their immediate family members are barred from entering the United States
• Secondary Sanctions: The order authorizes sanctions against any person who has “materially assisted” the ICC’s investigations into U.S. or allied personnel

Targets: The U.S. Treasury immediately designated ICC Prosecutor Karim Khan, two deputy prosecutors, and six ICC judges.

Global Fallout

The sanctions triggered a crisis in the international legal community.

European Defiance: The European Union considered activating “blocking statutes”—laws that prohibit EU companies from complying with extraterritorial U.S. sanctions—to protect its citizens working with the court.

Assembly of States Parties: Meeting in The Hague in December 2025, the Assembly was urged by NGOs like Human Rights Watch and Amnesty International to “oppose, not appease” the U.S. Amnesty described the sanctions as an “existential attack” on the rule of law.

Withdrawals: Emboldened by the U.S. stance, several nations moved to exit. Hungary formally withdrew in June 2025, and military juntas in Burkina Faso, Niger, and Mali announced their intent to withdraw.

This episode illustrates the central paradox of U.S. LOAC policy: the United States aggressively enforces the laws of war internally through the UCMJ but aggressively rejects external enforcement, viewing it as an infringement on sovereign authority.

Syria: A Legal Quandary

The collapse of the Assad regime in December 2024 presented the U.S. with a novel legal question: how to apply the laws of war in a country where the government has vanished, replaced by a designated terrorist organization.

The Fall of Damascus

On December 8, 2024, rebel forces led by Hay’at Tahrir al-Sham (HTS) seized Damascus. Bashar al-Assad fled to Russia, ending over 50 years of Ba’athist rule. The U.S. military, which maintained approximately 900 troops in eastern Syria to fight ISIS, suddenly found itself in a radically altered legal landscape.

The Status of Forces Problem

By February 2025, the U.S. increased its troop presence to roughly 2,000 to stabilize the security situation and prevent an ISIS resurgence.

Legal Basis: Previously, the U.S. justified its presence under the 2001 Authorization for Use of Military Force (AUMF) against terrorists and a theory of collective self-defense of Iraq. With the recognized government gone, the U.S. faced a dilemma.

The HTS Problem: The new interim government in Damascus was led by Ahmed Hussein Al Sharaa (formerly known as Abu Mohammed al-Jolani), the leader of HTS. HTS is a U.S.-designated Foreign Terrorist Organization.

Material Support vs. Humanitarian Obligation: Under International Humanitarian Law, an occupying power must facilitate humanitarian aid. However, U.S. domestic law prohibits providing “material support” to FTOs. If the FTO is the government, how does the U.S. coordinate aid delivery without violating its own counter-terrorism laws?

The Leahy Law in a Failed State

In 2025, reports surfaced of sectarian reprisals by opposition forces against Alawite and Druze communities. This triggered Leahy Law requirements.

Vetting: The U.S. had to rapidly vet partner forces to ensure U.S. weapons weren’t being used for ethnic cleansing.

Conditional Engagement: The U.S. adopted a policy of “conditional support,” maintaining sanctions on the Syrian state while demanding “inclusive governance” before granting recognition. This created a “twilight zone” where the U.S. was effectively occupying parts of a country run by a terrorist group it refused to recognize but had to coexist with.

Cluster Munitions: When Necessity Overrides Humanity

The conflict in Ukraine forced the U.S. to confront the tension between military necessity and humanitarian norms.

What Are DPICMs?

Dual-Purpose Improved Conventional Munitions (DPICM) are artillery shells that scatter dozens of smaller bomblets. They’re devastatingly effective against entrenched infantry and armor. They’re also banned by the Convention on Cluster Munitions, signed by over 100 countries (including most NATO allies), because unexploded bomblets act as de facto landmines for decades.

The US “1% Rule” and the Waiver

The U.S. isn’t a party to the Convention on Cluster Munitions. However, U.S. law generally prohibits the export of cluster munitions with a “dud rate” (failure rate) of greater than 1%.

The Reality: The U.S. stockpile of DPICMs has tested dud rates higher than 1% (often estimated around 2.35% or higher in combat conditions).

The Bypass: To support Ukraine’s counter-offensives in 2023, 2024, and 2025, President Biden utilized a National Security Waiver to bypass the 1% limit.

The Justification: The DoD argued that the military necessity of defeating Russian aggression, and the fact that Russia was already using cluster munitions with horrific 30-40% failure rates, outweighed the humanitarian risk.

The 2025 Aftermath

By late 2025, the “Cluster Munition Monitor” reported extensive use of these weapons by both sides. While they provided tactical advantages to Ukrainian forces, they left vast swathes of agricultural land contaminated.

The U.S. transfer highlighted a stark reality: when vital national security interests are at stake (the defeat of a strategic rival), the U.S. is willing to set aside humanitarian disarmament norms that it otherwise encourages.

The Future: Drones and AI

As we look toward the latter half of the decade, the laws of war are being strained by technologies that didn’t exist when the Geneva Conventions were written.

Redefining “Imminent Threat”

The U.S. drone program has long operated under a framework that lethal force outside active war zones is only permissible against a “continuing, imminent threat” to U.S. persons.

Policy Shift: In 2025, the Department of Homeland Security’s assessment and new FAA rules suggested a broadening of what constitutes an “imminent threat.”

Domestic Concerns: The FAA proposed allowing Beyond Visual Line of Sight drone operations for “imminent threats” within the U.S., creating concerns among civil liberties groups that the language of war was seeping into domestic policing.

Autonomous Weapons

The rise of Lethal Autonomous Weapons Systems (LAWS) robots that can select and engage targets without human intervention is the next frontier.

U.S. Policy: DoD Directive 3000.09, updated in 2023 and applied through 2025, doesn’t ban autonomous weapons. Instead, it mandates that systems be designed to allow for “appropriate levels of human judgment” over the use of force.

The Debate: The U.S. argues that AI can actually increase adherence to IHL by removing human rage, fear, and error from the firing decision. Critics argue that algorithms cannot make the qualitative judgment of “proportionality” (is the death of this child “excessive” relative to the target’s value?).

Rejection of a Ban: Throughout 2025, the U.S. continued to oppose a preemptive international treaty banning LAWS, preferring a non-binding “code of conduct” that preserves U.S. technological advantage.

Civilian Harm Mitigation

Following the tragic botched drone strike in Kabul in 2021 (which killed 10 civilians) and other incidents, the DoD launched a comprehensive overhaul of how it handles civilian casualties.

The Action Plan (2022-2025)

The Civilian Harm Mitigation and Response Action Plan (CHMR-AP) reached full implementation in FY 2025.

Center of Excellence: The DoD established a permanent center to analyze civilian harm data and integrate lessons learned into targeting doctrine.

Reporting: The “Annual Report on Civilian Casualties” released in May 2025 (covering 2024) assessed 2 confirmed incidents of civilian casualties in U.S. operations.

Critique: NGOs like the Center for Civilians in Conflict welcomed the standardized reporting but noted that the DoD’s standard for investigating claims remains too high, often dismissing reports from local media or NGOs that lack satellite corroboration.

Ex Gratia Payments: The U.S. formalized the system for “condolence payments” to families of victims. These are not admissions of legal liability (which would imply a war crime) but expressions of sympathy to maintain strategic legitimacy.

Where the US Stands

The United States’ relationship with the laws of war is best described as exceptionalist adherence. It maintains the world’s most sophisticated internal machinery for compliance (hundreds of JAGs, detailed manuals, satellite oversight) but fiercely resists any external authority that might second-guess its commanders.

US Legal Obligations at a Glance

As 2025 draws to a close, the U.S. finds itself in a paradoxical position: it’s the primary underwriter of the international rules-based order, yet it has sanctioned the primary international court designed to enforce it. It champions human rights, yet supplies cluster munitions that endanger civilians.

This duality isn’t an accident but a strategy, a belief that the “benevolent hegemony” of the United States requires the flexibility to act outside the strictest interpretations of international law to preserve the very order that law is meant to uphold. Whether this strategy can survive the fracturing of the global geopolitical landscape remains the defining question of the next decade.

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