Weapons Law
Legal Reviews of War Algorithms: From Cyber Weapons to AI Systems
States are obliged to conduct legal reviews of new weapons, means, and methods of warfare. Legal reviews of artificial intelligence (AI) systems pose significant legal and practical challenges due to their technical and operational features. This post explores how...
Tripwires to Trojans: Updating the Law of Booby-traps for the Digital Age
Articles of War has featured discussion of the law of armed conflict (LOAC) rules concerning booby-traps (see, e.g., here, here, here, and here). All have been based in the land domain. I am interested in the application of the idea in the cyber domain. Under the...
Belligerent Reprisals Series – Reprisals with Weapons
Editors’ note: This post is part of a series related to Francesco Romani’s book “Belligerent Reprisals from Enforcement to Reciprocity” published by Cambridge University Press. Francesco’s impressive work on belligerent reprisals and this series are welcome reminders...
Future of Warfare and Law Series – Legal Reviews of Autonomous Weapons at the Tactical Edge
Editors’ note: This post is part of a series featuring topics discussed during the Third Annual Future of Warfare and the Law Symposium. Christina Colclough’s introductory post is available here. The Future of Warfare and the Law Symposium (hereinafter, the...
Future of Warfare and Law Series – The Law and LAWS
Editors’ note: This post is part of a series featuring topics discussed during the Third Annual Future of Warfare and the Law Symposium. Christina Colclough’s introductory post is available here. In May of 2025, the third Future of Warfare and the Law Symposium...
Tentative Remarks on Ukraine’s Suspension of the Ottawa Convention
On June 29, 2025, the President of Ukraine signed a decree on the withdrawal of Ukraine from the Convention on the Prohibition of the Use, Stockpiling, Production and Transfer of Anti-Personnel Mines and on their Destruction, otherwise known as the Ottawa Convention....
Unleashing Drone Dominance: Rethinking Department of Defense Weapons Reviews
In November 2001, the United States conducted what is considered to be the first ever armed drone attack in Afghanistan. Over the next twenty years, the United States dominated the production of large unmanned systems that cost millions of dollars each to produce. In...
CyCon 2025 Series – Legal Reviews of Military Artificial Intelligence Capabilities
Editors’ note: This post is part of a series that features presentations at this year’s 17th International Conference on Cyber Conflict (CyCon) in Tallinn, Estonia. Its subject will be explored further as part of a chapter in the forthcoming book International Law and...
Is Nuclear Weapons Law Stopping the Nukes?
Editors’ Note: This post draws upon the book, The Law on Nuclear Weapons: An International Commentary edited by the authors and published in 2025 by Edward Elgar. It is always difficult to know for sure why political leaders and senior members of the armed forces...
Did China Just Violate the Biological Warfare Convention?
In early June, the U.S. Federal Bureau of Investigation (FBI) arrested two nationals of the People’s Republic of China for conspiracy to smuggle a fungus called Fusarium graminearum into the United States, which scientific literature classifies as an agroterrorism...
What Is Left After Leaving Ottawa?
With 165 member States (at the time of writing), the Ottawa Convention is arguably the most widely recognized international treaty on conventional weapons. It was long regarded as a triumph of civil society, with progress reported on an annual basis. Even the fact...
Diverging Standards in the Legal Review of LAWS
In May 2025, Anduril Industries publicly unveiled Fury (YFQ-44A), a next-generation autonomous aircraft currently under evaluation by the U.S. Air Force as part of its Collaborative Combat Aircraft (CCA) program. Fury takes its first test flights this summer. The goal...
Ukraine Symposium – Captured Enemy Weapons
The Russian military has fielded a new weapon in its conflict with Ukraine. In recent weeks, at least one frontline Russian unit was observed operating an American-made Bradley M2A2 infantry fighting vehicle, and Russia is believed to possess nearly a dozen others....
Leaving Ottawa: Lithuania Denounces the Anti-Personnel Mines Convention
Significant changes are happening on NATO’s eastern flank. In 2024 Lithuania denounced the Convention on Cluster Munitions. More recently, on May 8, 2025, Lithuania announced its decision to withdraw from the Convention on the Prohibition of the Use, Stockpiling,...
The Disarmament Treaties Prohibiting Anti-Personnel Mines and Cluster Munitions: Separating Fact from Fiction
In recent months, there has been considerable criticism in scholarship, and in opinion editorials in several newspapers, of the content and impact of the two conventional disarmament treaties: the 1997 Convention on the Prohibition of the Use, Stockpiling, Production...
Cluster Munitions and Anti-Personnel Land Mines: An Explainer
Russia’s ongoing invasion of Ukraine has ignited discussions within and between NATO States concerning the international conventions that ban the use, production, transfer, and stockpiling of cluster munitions and anti-personnel landmines, and require the destruction...
Assessing the Ottawa Anti-Personnel Mine Convention Withdrawals
As security along their borders has deteriorated, Eastern European, Baltic, and Nordic States have scrambled to update and adapt their national defense strategies. Nearly all these States have publicly committed to significantly increase defense spending. To...
Booby-traps and “Apparently Harmless” Portable Objects
Recent hostilities in eastern Europe and the Middle East have generated significant interest in issues of law of armed conflict (LOAC) compliance. Notably, several incidents have led to close scrutiny of the LOAC rules on the use of booby-traps (see e.g., here, here,...
The Future of Warfare: National Positions on the Governance of Lethal Autonomous Weapons Systems
Lethal autonomous weapons systems (LAWS), such as drones and autonomous missile systems, are no longer a theoretical concern. Indeed, they are finding their way onto the battlefield. Amid growing international concern, States have articulated a range of positions on...
Ukraine Symposium – The Budapest Memorandum’s History and Role in the Conflict
Last month of 2024 marked the 30th anniversary of the signing of the Budapest Memorandum, part of an agreement by which Ukraine gave up its nuclear arsenal in return for security assurances by Russia, the United States, and the United Kingdom. The Memorandum, signed...
The Drone Threat, the Laser Response, and the Law – Part II
The first part of this two-part post, described and explained the weapons law principles and rules that apply to suicide or kamikaze drones. It also set forth and explained applicable targeting law principles and rules and addressed the legality of mass attacks...
The Drone Threat, the Laser Response, and the Law – Part I
In conflicts during the last few years, unmanned air weapons, commonly referred to as drones, have increasingly been used to undertake attacks of ground targets. These attacks have recently involved large numbers of these drones, often directed at multiple targets....
Dutch District Court Judgment on Military Support to and Trade with Israel
On Friday 13 December 2024, the District Court of the Hague handed down its judgment in a torts case related to the Netherlands’ military support to and trade cooperation with Israel. Al-Haq and nine other civil society organizations (referred to collectively as...
Finland, Territorial Security, and Anti-personnel Mines
This post outlines select international weapons law obligations of Finland relating to anti-personnel mines against the backdrop of its evolving national security situation. It identifies an array of legal, operational, and technical issues that will bear on any...
Exploding Pagers and the Law
Reports emerged on 17 September 2024 that, from about 15:45 that day local time, a large number of pagers used by Hezbollah personnel in Lebanon exploded spontaneously and virtually simultaneously. At the time of writing, nine persons are reported to have died and...
Russia’s Alleged Nuclear Anti-Satellite Weapon: International Law and Political Rhetoric
The development and testing of anti-satellite weapons (ASATs), as well as debates concerning the legal and policy implications of ASAT testing and use, have existed since soon after the dawn of the Space Age. The centrality of these issues has waxed and waned over...
Distinction and the Rule of Perfidy within the Electromagnetic Spectrum
Editors' note: This post is based on course work that Luke Gigliotti completed in his final year as a cadet at the U.S. Military Academy West Point. The electromagnetic spectrum (EMS) plays a crucial role in contemporary armed conflicts. The challenge for military...
Flamethrowers: A Fiery Legacy and Uncertain Future?
In warfare, few weapons are as terrifying as the flamethrower. Horrific imagery captured in iconic photographs from the First and Second World Wars cemented its reputation for inflicting excruciating burns and long-term physical and psychological effects. Given the...
Caltrop: An Ancient Weapon in Modern Warfare
Recent reports indicate that Ukraine has modified drones to deliver and disperse a weapon of ancient design in its fight against Russia. The weapon, known as a caltrop, is a spiked device that can be strewn in large numbers, sometimes connected by a chain, across a...
Ukraine Symposium – Russia’s Use of Riot Control Agents in Ukraine
Russian forces are reportedly using non-lethal chemical weapons known as riot control agents (RCA) to flush combatants out of trenches in eastern Ukraine before attacking them with conventional munitions. According to a report published by Reuters on April 17, the...
National Security Memorandum 20 and the Challenge of Operational End-Use Monitoring
Today, May 8, was the deadline for the Departments of Defense (DoD) and State to answer tough questions about how U.S. supplied weapons are being used in today’s conflicts, including those in Gaza and Ukraine. It appears that the delivery of their reports to Congress...
In Honor of Yoram Dinstein – Command Responsibility in an Era of New Weapons
Editors’ note: This post is part of a series to honor Professor Yoram Dinstein, who passed away on Saturday February 10, 2024. These posts recognize Professor Dinstein’s work and the significant contribution his scholarship has made to our understanding of...
MARWAN 1: How U.S. Central Command Transferred Seized Iranian Ammunition to Ukraine
On December 1, 2022, the USS Lewis B. Puller, an expeditionary mobile base ship assigned to the U.S. 5th Fleet and U.S. Naval Forces Central Command, intercepted a fishing trawler, the Marwan 1 (Marwan), a flagless vessel, in the Gulf of Oman. A security team from the...
State Submissions on the Legal Review of AWS and Possible Good Practices
The review of weapons, means, and methods of warfare for compliance with international law has attracted significant attention during the international debate about the regulation and use of autonomous weapon systems (AWS). Legal reviews have been cited as one tool...
AWS Legal Review Series – Protracted Debate, Incremental Progress, Unexpected Outcomes
This post appears as part of a series on the legal review of autonomous weapon systems. An introductory post by Professors Rain Liivoja and Sean Watts provides an overview of the series. High Contracting Parties to the Convention on Certain Conventional Weapons (CCW)...
Israel – Hamas 2024 Symposium – Reflections on the Invocation of Common Article 1
The South Africa v. Israel case at the International Court of Justice (ICJ) concerning alleged violations of the Genocide Convention during the Israel-Hamas war has broader implications than the core question at the heart of that proceeding. One consequence became...
AWS Legal Review Series – Transparency and the Experience of the Netherlands
This post appears as part of a series on the legal review of autonomous weapon systems. An introductory post by Professors Rain Liivoja and Sean Watts provides an overview of the series. In 1978, the Netherlands implemented the national review obligations of Article...
An Assessment of Russia’s Withdrawal from the Comprehensive Test Ban Treaty
On November 2, 2023, Russia’s President Vladimir Putin signed a law withdrawing the country’s ratification of the 1996 Comprehensive Test Ban Treaty (CTBT). This multilateral treaty prohibits State parties from conducting, encouraging, or participating in any nuclear...
Lieber Studies Big Data Volume – Big Data and Armed Conflict – Legal Issues Above and Below the Armed Conflict Threshold
Editor’s note: This is the first post in a symposium addressing themes from a new book entitled Big Data and Armed Conflict: Legal Issues Above and Below the Armed Conflict Threshold, the ninth in the Lieber Institute’s Lieber Studies series with Oxford University...
Nova 2, Legion-X, and the AI Political Declaration
The race to develop autonomous weapons systems for military deployment has entered a new phase, with the use of artificial intelligence (AI) technology for the navigation of small drones in active combat. In the latest round of Gaza conflicts commencing on October 7,...
Arms Exporters’ Corporate Liability for Due Diligence Failures
The intensification of the armed conflict between Israel and Hamas is reported to have led to another surge in international arms sales. In fact, lately, new weapon systems have been in increasing demand from various countries. The Stockholm International Peace...
Israel – Hamas 2023 Symposium – White Phosphorus and International Law
Editor’s note: The authors’ original version of this post omitted citations to two sources, namely LTC Matthew J. Aiesi’s post on Lawfare dated November 26, 2019, and a Human Rights Watch report dated October 12, 2023. On 10 November, we corrected the post to include...
The Biden Administration’s Decision to Transfer Cluster Munitions to Ukraine: Legal and Policy Considerations
The Biden administration recently announced the approval of a new arms package for Ukraine that will, for the first time, include the provision of cluster munitions. This decision follows media reporting indicating that the administration had been “actively...
Ukraine Symposium – The Legality of Depleted Uranium Shells and Their Transfer to Ukraine
The decision by the United Kingdom (UK) in March 2023 to transfer depleted uranium tank shells to Ukraine provoked a fierce reaction from senior Russian political and military officials. President Vladimir Putin warned that Moscow would “respond accordingly, given...
The Law in War: A Concise Overview
When we first plotted our plan to write the 1st edition of this book, our goal was to offer an accessible narrative overview of international humanitarian law for both lawyers and non-lawyers interested in the topic. To that end, the original 2018 edition addressed...
Ukraine Symposium – Landmines and the War in Ukraine
Human Rights Watch has documented the use of both anti-vehicle and anti-personnel landmines in Ukraine. Following reports that Ukraine is using anti-personnel landmines (APLs) in violation of the Ottawa Convention, the Ukrainian authorities acknowledged this...
Ukraine Symposium – Field-Modified Weapons under the Law of War
Combatants in armed conflict may choose to modify weapons in the field for a variety of reasons. They may modify them to improve their reliability. They may alter them to increase their range or accuracy. Or they may adapt them to novel purposes. During the...
Responsible AI Symposium – Responsible AI and Legal Review of Weapons
Editor’s note: The following post highlights a subject addressed at an expert workshop conducted by the Geneva Centre for Security Policy focusing on Responsible AI. For a general introduction to this symposium, see Tobias Vestner’s and Professor Sean...
The al-Zawahiri Strike and the Law of Armed Conflict
Just after daybreak on July 31, the United States killed Ayman al-Zawahiri, Osama bin Laden’s former deputy and the current leader of al-Qaeda. Two Hellfire missiles struck him on the balcony of his home in Kabul. Nearby residents reported a loud blast along with an...
A New Political Declaration on Civilian Harm: Progress or Mythical Panacea?
On June 17, against a backdrop of the Russian invasion of Ukraine that has now killed or wounded over 11,000 civilians in a little more than four months, a group of States, the International Committee of the Red Cross (ICRC), and non-governmental organizations (NGOs)...
Coding the Law of Armed Conflict: First Steps
[Editor’s note: The following post highlights a subject addressed in the Lieber Studies volume The Future Law of Armed Conflict, which was published 27 May 2022. For a general introduction to this volume, see Professor Matt Waxman’s introductory post.] Killer...
Déjà Vu: International Landmine Law and the New U.S. Landmine Policy
Following a “comprehensive policy review,” the Biden Administration announced significant changes to U.S. Anti-Personnel Landmine (APL) policy on June 21, 2022. The new policy reverses most aspects of the Trump Administration’s 2020 policy. In fact, since the Clinton...
Hunter 2-S Swarming Attack Drones: Legal & Ethical Dimensions
Halcon, a defense company based in the United Arab Emirates, unveiled its aerial fleet of swarming drones—Hunter 2-S—at the Unmanned System Exhibition and Conference in Abu Dhabi on February 21, 2022. The small-sized Hunter 2-S modular launching system is the latest...
Are Thermobaric Weapons Lawful?
The Russian Federation has deployed and likely used thermobaric weapons during its invasion of Ukraine. Ukraine’s ambassador to the United States alleged that Russia “used the vacuum bomb today, which is actually prohibited by the Geneva Conventions,” while American...
Are Molotov Cocktails Lawful Weapons?
A frequent feature of violent riots and revolts, the Molotov cocktail has reappeared in reports of Ukraine’s preparations to resist the ongoing Russian invasion. Although undoubtedly symbolic of resolve to resist using all means available, whether Ukrainians’ use of...
Reentering the Loop
The warfighting advantages of using lethal autonomous systems, and the potential costs of not using them, seem to guarantee their role in future armed conflict. This post argues that optimizing their effectiveness involves not only improving their independent...
Why Binding Limitations on Autonomous Weapons Will Remain Elusive
Recent calls to abandon existing and ongoing legal processes to develop regulations for autonomous weapons should be evaluated cautiously or even suspiciously. This post proposes a more productive path toward effective regulation and important international consensus...
Hays Parks’s Influence on Cyberspace Operations Capabilities
The recent Articles of War series honoring Hays Parks was a fitting tribute to a great American lawyer that reintroduced his work to the military legal community and its newest generations. The series referenced a seminal paper in which he addressed international...
Cognitive Lethal Autonomous Weapons Systems (CLAWS)
With the debut of lethal autonomous weapons systems (LAWS) in combat, opponents of LAWS have called on States to fast-track the creation of international law that either bans the use of these weapons or mandates meaningful human control over them. If LAWS are used...
Hays Parks on the Means and Methods of Warfare
Hays Parks was one of the leading voices of the United States’ view of the law of war over the last 50 years, and one of the founding fathers of the field of operational law in the U.S. military. Both of us are honored to have either worked directly with him or to...
Symposium Intro: Hays Parks’s Influence on the Law of War
Most developments and codifications of the law of war have been responses to the evolving character of warfare. Indeed, a timeline of law of war treaties reads like a chronicle of changes in the tactics, technologies, and participants in war. Yet like war itself,...
LAWS Debate at the United Nations: Moving Beyond Deadlock
The United Nations is once again hosting a Group of Governmental Experts tasked to report on emerging technologies in the area of lethal autonomous weapons systems (LAWS). Further debate on this subject at the conceptual level, such as its definition, accountability,...
The U.S. Landmine Policy Complies with International Law
In late January, the United States replaced the Obama Administration’s 2016 landmine policy, which was first introduced in 2014. That policy had proscribed the use of antipersonnel landmines beyond the Korean peninsula. In taking this step, Defense Secretary...
