Ukraine Symposium – The Legality of Depleted Uranium Shells and Their Transfer to Ukraine


| Mar 24, 2023

Depleted Uranium Transfer

​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 that the collective West is starting to use weapons with a ‘nuclear component’.” Sergei Shoigu, Russia’s Minister of Defence, claimed that the decision left “fewer and fewer steps” before a potential “nuclear collision” between Russia and the West. Given the heated rhetoric, this post assesses the legality under the law of armed conflict of the use of depleted uranium shells as a means of warfare, as well as the compatibility of the UK’s decision on transfer with its obligations under international law, including disarmament law.

Law of Armed Conflict Considerations

The law of armed conflict (LOAC) prohibits the use of any weapon according to two general rules. Either the weapon is inherently indiscriminate or it is of a nature to cause superfluous injury or unnecessary suffering. In either case, a weapon falling foul of the respective rule may not be used as a means of warfare.

The assessment of the first of the two rules can be dispensed with in short order. An indiscriminate weapon is one that can neither be directed at a specific military objective nor can its effects be limited in time and space in accordance with LOAC stipulations. The shells being transferred are specifically for use in the Challenger II tanks the UK is also providing to Ukraine. The Challenger II is fitted with a 120mm rifled tank gun that is targeted using a laser-range finder. This adjusts the gun before firing, taking into account wind, temperature, and the direction the target vehicle is moving. The fact that shells contain depleted uranium does not diminish their precision. While the requisite accuracy demanded by the principle of distinction lacks a specific figure in contemporary law, such as a defined circular error probable (CEP), the 120mm gun on the Challenger is certainly within its confines.

A little more reflection is needed when it comes to the assessment of the “superfluous injury” rule. This calls for understanding of both what depleted uranium is and what it is not. Depleted uranium is a dense metal generated as a by-product of enriching natural uranium for nuclear fuel. It is not material that is capable of a nuclear chain reaction. That said, depleted uranium is still radioactive—and therefore neither inert nor harmless—although its radioactivity is much lower than is the original nuclear material. It is used in armour-piercing shells to enhance their penetration. Depleted uranium munitions, which were developed by the United States and UK in the 1970s, were first used in the Gulf War in 1991, and then in Kosovo in 1999, and during the Iraq War in 2003.

As detailed by the UN Secretary-General in his 2016 report, “Effects of the use of armaments and ammunitions containing depleted uranium,” the International Atomic Energy Agency (IAEA) has conducted a number of studies into the use of depleted uranium shells and bombs. As a result of their analysis, the IAEA has concluded that post-conflict depleted uranium residues dispersed in the environment do not pose a radiological hazard to the local population. The “presence of large fragments of, or complete, depleted uranium ammunition” could, however, “result in exposures of radiological significance to individuals who are in direct contact with those radioactive materials, for example, if they are collected as souvenirs or when military vehicles which have been hit by such ammunition are reprocessed for scrap metal” (UN doc. A/71/139, 2016: 9). The United Nations Environment Programme (UNEP), which has evaluated studies on the impact of depleted uranium munitions on military veterans, has identified “[n]o clinically significant pathology related to radiation exposure” (UN doc. A/71/139, 2016: 10).

The customary law prohibition of means of warfare of a nature to cause superfluous injury or unnecessary suffering only renders unlawful those weapons whose military necessity is clearly outweighed by the expected injury or suffering inflicted on a combatant. In particular, injuries provoked by an anti-personnel weapon that are objectively gratuitous or are substantially more than necessary to render a soldier hors de combat are unlawful.

Depleted uranium shells sharpen on impact, which further increases their ability to bore through armour, and they ignite after contact. As the U.S. Environmental Protection Agency has observed, depleted uranium is both a toxic chemical and radiation health hazard when inside the body. But the military advantage offered by depleted uranium shells—their significantly enhanced armour-piercing capability against other tanks—is assuredly greater than is the relatively minimal risk to fighters (based on the available evidence). This also extends to the hazard posed to military explosive ordnance disposal personnel engaged in post-conflict clean-up. One may therefore conclude that the use of depleted uranium tank shells in armed conflict is not inherently unlawful, either because the shells are indiscriminate or because they inevitably cause unnecessary suffering.

Transfer Considerations

Of course, any weapon may be used unlawfully, and tank shells are no exception. This leads to consideration of whether there are any grounds that require the UK to refrain from transferring them to Ukraine. The most obvious basis would be that they are being used to target civilians or the civilian population as such, or in indiscriminate attacks. Every State is obligated under the law governing State responsibility not to aid or assist another State to commit an internationally wrongful act (i.e., a violation of international law). This is set forth in Article 16 of the International Law Commission’s 2001 Draft Articles on the Responsibility of States for Internationally Wrongful Acts.

According to this provision, which reflects customary law, a State that aids or assists another in the commission of an internationally wrongful act by the latter is itself internationally responsible for doing so if that State does so “with knowledge of the circumstances of the internationally wrongful act” and where the act would be internationally wrongful if committed by that State. Attacking civilians and indiscriminate attacks in the conduct of hostilities are both clear and serious violations of international law and would be violations by the UK just as they would be by Ukraine.

More specifically, and as a matter of treaty law, by virtue of its adherence to the UN Arms Trade Treaty (ATT), the UK may not export munitions for battle tanks to any State, including Ukraine, where it has under Article 2(1) or of items covered under Article 3 or Article 4, if it has knowledge at the time of authorization that the munitions would be used in attacks directed against civilian objects or civilians protected as such, or if there is an overriding risk that they would be used to commit or facilitate a serious violation of international humanitarian law (i.e., LOAC). These rules are set forth in Articles 2(1)(a), 3, 6(3), and 7(1)(b)(i) and (3) of the ATT.

The ATT demands that the UK have first assessed the risk of Ukraine breaching its LOAC obligations, in particular in the course of tank warfare. The most obvious place to seek evidence, aside from its own internal reporting, would be the Independent International Commission of Inquiry on Ukraine mandated by the UN Human Rights Council in its Resolution 49/1 of 4 March 2022. The Commission of Inquiry on Ukraine issued its latest report in March 2023 in which it assessed 25 attacks involving explosive weapons in populated areas. None of the attacks concerned tanks. The Commission concluded at Paragraph 23 that: “A small number of indiscriminate attacks were likely committed by Ukrainian armed forces.” Ukraine has also, the Commission believes, used cluster munitions indiscriminately. It has further used anti-personnel mines, in serious violation of its treaty obligations under the 1997 Anti-Personnel Mine Ban Convention. This use amounts to war crimes under Ukrainian domestic law: under Article 438 of its Criminal Code.

These serious violations of LOAC should give pause for thought. But if appropriate mitigation measures are taken by the UK, in accordance with Article 7(2) of the ATT, and meaningful monitoring is ensured of their use, this would not render the decision to transfer the depleted uranium shells (or indeed the Challenger II tanks) unlawful. Ukraine must comply rigorously with its own obligations under LOAC and ensure full accountability for all those who commit serious violations of LOAC. The serious and pervasive violations perpetrated by Russian forces, as documented by the Commission of Inquiry on Ukraine, and by the recent arrest warrant issued by the International Criminal Court, do not negate this duty.

Concluding Thoughts

The UK, the United States, and many other nations have supported Ukraine to resist and repel the renewed Russian aggression that began on 24 February 2022. Only lawful weapons may be provided and only to the extent that Ukraine complies with its LOAC obligations. Today, we may conclude that the decision by the United Kingdom to transfer depleted uranium shells to Ukraine is compliant with international law.


Stuart Casey-Maslen is Extraordinary Professor of International Law at the Centre for Human Rights of the University of Pretoria.



Photo credit: Sergeant Steve Blake RLC, U.K. Ministry of Defence


Symposium Intro: Ukraine-Russia Armed Conflict

by Sean WattsWinston WilliamsRonald Alcala

February 28, 2022

Russia’s “Special Military Operation” and the (Claimed) Right of Self-Defense

by Michael N. Schmitt

February 28, 2022

Legal Status of Ukraine’s Resistance Forces

by Ronald Alcala and Steve Szymanski

February 28, 2022

Cluster Munitions and the Ukraine War

by William H. Boothby

February 28, 2022

Neutrality in the War against Ukraine

by Wolff Heintschel von Heinegg

March 1, 2022

The Russia-Ukraine War and the European Convention on Human Rights

by Marko Milanovic

March 1, 2022

Deefake Technology in the Age of Information Warfare

by Hitoshi Nasu

March 1, 2022

Ukraine and the Defender’s Obligations

by Eric Jensen

March 2, 2022

Are Molotov Cocktails Lawful Weapons?

by Sean Watts

March 2, 2022

Application of IHL by and to Proxies: The “Republics” of Donetsk and Luhansk

by Marco Sassòli

March 3, 2022

Closing the Turkish Straits in Times of War

by Raul (Pete) Pedrozo

March 3, 2020

The Abuse of “Peacekeeping”

by Alexander Gilder

March 3, 2022

Prisoners of War in Occupied Territory

by Geoff Corn

March 3, 2022

Combatant Privileges and Protections

by Laurie R. Blank

March 4, 2022

Siege Law

by Sean Watts

March 4, 2022

Russia’s Illegal Invasion of Ukraine & the Role of International Law

by Michael Kelly

March 4, 2022

Russian Troops Out of Uniform and Prisoner of War Status

by Chris Koschnitzky and Michael N. Schmitt

March 4, 2022

On War

by Andrew Clapham

March 5, 2022

Providing Arms and Materiel to Ukraine: Neutrality, Co-belligerency, and the Use of Force

by Michael N. Schmitt

March 7, 2022

Keeping the Ukraine-Russia Jus ad Bellum and Jus in Bello Issues Separate

by Rob Mclaughlin

March 7, 2022

The Other Side of Civilian Protection: The 1949 Fourth Geneva Convention

by Jelena Pejic

March 7, 2022

Special Forces, Unprivileged Belligerency, and the War in the Shadows

by Ken Watkin

March 8, 2022

Accountability and Ukraine: Hurdles to Prosecuting War Crimes and Aggression

by Lauren Sanders

March 9, 2022

Remarks on the Law Relating to the Use of Force in the Ukraine Conflict

by Terry D. Gill

March 9, 2022

Consistency and Change in Russian Approaches to International Law

by Jeffrey Kahn

March 9, 2022

The Fog of War, Civilian Resistance, and the Soft Underbelly of Unprivileged Belligerency

by Gary Corn

March 10, 2022

Common Article 1 and the Conflict in Ukraine

by Marten Zwanenburg

March 10, 2022

Levée en Masse in Ukraine: Applications, Implications, and Open Questions

by David Wallace and Shane Reeves

March 11, 2022

The Attack at the Zaporizhzhia Nuclear Plant and Additional Protocol I

by Tom Dannenbaum

March 13, 2022

The Russia-Ukraine War and the Space Domain

by Timothy GoinesJeffrey BillerJeremy Grunert

March 14, 2022

Fact-finding in Ukraine: Can Anything Be Learned from Yemen?

by Charles Garraway

March 14, 2022

Status of Foreign Fighters in the Ukrainian Legion

by Petra Ditrichová and Veronika Bílková

March 15, 2022

Law Applicable to Persons Fleeing Armed Conflicts

by Julia Grignon

March 15, 2022

Ukraine’s Legal Counterattack

by Michael Kelly

March 17, 2022

The ICJ’s Provisional Measures Order: Unprecedented

by Ori Pomson

March 17, 2022

Displacement from Conflict: Old Realities, New Protections?

by Ruvi Ziegler

March 17, 2022

A No-Fly Zone Over Ukraine and International Law

by Michael N. Schmitt

March 18, 2022

Time for a New War Crimes Commission?

by Diane Marie Amann

March 18, 2022

Portending Genocide in Ukraine?

by Adam Oler

March 21, 2022

Are Mercenaries in Ukraine?

by Robert Lawless

March 21, 2022

Abducting Dissent: Kidnapping Public Officials in Occupied Ukraine

by Katharine Fortin

March 22, 2022

Are Thermobaric Weapons Unlawful?

by Matt Montazzoli

March 23, 2022

A Ukraine No-Fly Zone: Further Thoughts on the Law and Policy

by Terry D. Gill

March 23, 2022

The War at Sea: Is There a Naval Blockade in the Sea of Azov?

by Martin Fink

March 24, 2022

Deportation of Ukrainian Civilians to Russia: The Legal Framework

by Michael N. Schmitt

March 24, 2022

Weaponizing Food

by Michael N. Schmitt

March 28, 2022

Command Responsibility and the Ukraine Conflict

by Noëlle Quénivet

March 30, 2022

The Siren Song of Universal Jurisdiction: A Cautionary Note

bySteve Szymanski and Peter C. Combe

April 1, 2022

A War Crimes Primer on the Ukraine-Russia Conflict

by Sean Watts and Hitoshi Nasu

April 4, 2022

Russian Booby-traps and the Ukraine Conflict

by Michael N. Schmitt

April 5, 2022

The Ukraine Conflict, Smart Phones, and the LOAC of Takings

by Gary Corn

April 7, 2022

War Crimes against Children

by Véronique Aubert

April 8, 2022

Weaponizing Civilians: Human Shields in Ukraine

by Michael N. Schmitt

April 11, 2022

Unprecedented Environmental Risks

by Karen Hulme

April 12, 2022

Maritime Exclusion Zones in Armed Conflicts

by Raul (Pete) Pedrozo

April 12, 2022

Ukraine’s Levée en Masse and the Obligation to Ensure Respect for LOAC

by Jann K. Kleffner

April 14, 2022

Cultural Property Protection in the Ukraine Conflict

by Dick Jackson

April 14, 2022

Results of a First Enquiry into Violations of International Humanitarian Law in Ukraine

by Marco Sassòli

April 14, 2022

Comprehensive Justice and Accountability in Ukraine

by Chris Jenks

April 15, 2022

Maritime Neutrality in the Russia-Ukraine Conflict

by David Letts

April 18, 2022

Cyber Neutrality, Cyber Recruitment, and Cyber Assistance to Ukraine

by Nicholas Tsagourias

April 19, 2022

Defiance of Russia’s Demand to Surrender and Combatant Status

by Chris Koschnitzky and Steve Szymanski

April 22, 2022

The Montreux Convention and Turkey’s Impact on Black Sea Operations

by Adam Aliano and Russell Spivak

April 25, 2022

Lawful Use of Nuclear Weapons

by Jay Jackson and Kenneth “Daniel” Jones

April 26, 2022

Litigating Russia’s Invasion of Ukraine

by Lawrence Hill-Cawthorne

April 27, 2022

Military Networks and Cyber Operations in the War in Ukraine

by Heather Harrison Dinniss

April 29, 2022

Building Momentum: Next Steps towards Justice for Ukraine

by Philippa Webb

May 2, 2022

Counternormativity and the International Order

by Dan E. Stigall

May 3, 2022

Destructive Counter-Mobility Operations and the Law of War

by Sean Watts and Winston Williams

May 5, 2022

Are We at War?

by Michael N. Schmitt

May 9, 2022

The Ukraine Conflict and the Future of Digital Cultural Property

by Ronald Alcala

May 13, 2022

Neutral State Access to Ukraine’s Food Exports

by James Kraska

May 18, 2022

Negotiating an End to the Fighting

by Michael N. Schmitt

May 24, 2022

Is the Law of Neutrality Dead?

by Raul (Pete) Pedrozo

May 31, 2022

Effects-based Enforcement of Targeting Law

by Geoff Corn and Sean Watts

June 2, 2022

U.S. Offensive Cyber Operations in Support of Ukraine

by Michael N. Schmitt

June 6, 2022

War Sanctions Steadily Degrade the Russian Maritime Sector

by James Kraska

June 7, 2022

The Atrocity Crimes Advisory Group & Ukrainian Prosecutions of Russian POWs – Part 1

by Chris Jenks

June 22, 2022

The Atrocity Crimes Advisory Group & Ukrainian Prosecutions of Russian POWs – Part 2

by Chris Jenks

June 24, 2022

The Atrocity Crimes Advisory Group & Ukrainian Prosecutions of Russian POWs – Part 3

by Chris Jenks

June 28, 2022

Putting “Overall Control” to the Test of the Third Geneva Convention

by Alessandra Spadaro

July 6, 2022

The Risk of Commercial Actors in Outer Space Drawing States into Armed Conflict

by Tara Brown

July 8, 2022

The Release of Prisoners of War

by Jeroen van den Boogaard

July 8, 2022

The Attack on the Vasily Bekh and Targeting Logistics Ships

by James Kraska

July 11, 2022

Lessons from Syria’s Ceasefires

by Marika Sosnowski

July 12, 2022

Documentation and Investigation Responses to Serious International Crimes

by Brianne McGonigle Leyh

July 13, 2022

Rebel Prosecutions of Foreign Fighters in Ukraine

by René Provost

July 15, 2022

Forced Civilian Labor in Occupied Territory

by Michael N. Schmitt

August 2, 2022

Forced Conscription in the Self-Declared Republics

by Marten Zwanenburg

August 8, 2022

Amnesty International’s Allegations of Ukrainian IHL Violations

by Michael N. Schmitt

August 8, 2022

Oil Tankers as “Environmental Time Bombs,” or Not

by Mark Jessup

August 12, 2022

The Escalating Military Use of the Zaporizhzhia Nuclear Plant

by Tom Dannenbaum

August 22, 2022

Protected Zones in International Humanitarian Law

by Michael N. Schmitt

August 24, 2022

Photos of the Dead

by William Casey Biggerstaff

August 19, 2022

Deception and the Law of Armed Conflict

by William Casey Biggerstaff

September 8, 2022

Data-Rich Battlefields and the Future of LOAC

by Shane ReevesRobert Lawless

September 12, 2022

Russian Crimes Against Children

by Oleksii KaminetskyiInna Zavorotko

September 14, 2022

Targeting Leadership

by Mehmet Çoban

September 16, 2022

Illegality of Russia’s Annexations in Ukraine

by Lauri Mälksoo

October 3, 2022

Russia’s Forcible Transfer of Children

by Alison Bisset

October 5, 2022

The Kerch Strait Bridge Attack, Retaliation, and International Law

by Marko MilanovicMichael N. Schmitt

October 12, 2022

Russian Preliminary Objections at the ICJ: The Case Must Go On?

by Ori Pomson

October 13, 2022

The Complicity of Iran in Russia’s Aggression and War Crimes in Ukraine

by Marko Milanovic

October 19, 2022

Attacking Power Infrastructure under International Humanitarian Law

by Michael N. Schmitt

October 20, 2022

Dirty Bombs and International Humanitarian Law

by Michael N. Schmitt

October 26, 2022

Doxing Enemy Soldiers and the Law of War

by Eric Talbot JensenSean Watts

October 31, 2022

Are Civilians Reporting With Cell Phones Directly Participating in Hostilities?

by Michael N. SchmittWilliam Casey Biggerstaff

November 2, 2022

Using Cellphones to Gather and Transmit Military Information, A Postscript

by Michael N. Schmitt

November 4, 2022

State Responsibility for Non-State Actors’ Conduct

by Jennifer Maddocks

November 4, 2022

Reparations for War: What Options for Ukraine?

by Luke Moffett

November 15, 2022

Further Thoughts on Russia’s Campaign against Ukraine’s Power Infrastructure

by Michael N. Schmitt

November 25, 2022

Russia’s Allegations of U.S. Biological Warfare in Ukraine – Part I

by Robert Lawless

December 2, 2022

Russia’s Allegations of U.S. Biological Warfare in Ukraine – Part II

by Robert Lawless

December 9, 2022

The THeMIS Bounty Part I: Seizure of Enemy Property

by Christopher Malis and Hitoshi Nasu

December 12, 2022

Classification of the Conflict(s)

by Michael N. Schmitt

December 14, 2022

The THeMIS Bounty Part II: Stealing Enemy Technology

by Christopher Malis, Hitoshi Nasu

December 16, 2022

The “I Want to Live” Project and Technologically-Enabled Surrender

by David WallaceShane Reeves

January 13, 2023

UN Peacekeepers and the Zaporizhzhia Nuclear Plant

by Alexander Gilder

January 20, 2023

What’s in a Name? Getting it Right for the Naval “Drone” Attack on Sevastopol

by Caroline Tuckett

January 23, 2023

Ukraine’s “Suicide Drone Boats” and International Law

by Charles M. Layne

January 25, 2023

The Impact of Sanctions on Humanitarian Aid

by Alexandra Francis

January 27, 2023

A Wagner Group Fighter in Norway

by Camilla Cooper

February 1, 2023

The Legal and Practical Challenges of Surrendering to Drones

by William Casey Biggerstaff,Caitlin Chiaramonte

February 8, 2023

Field-Modified Weapons under the Law of War

by Ronald Alcala

February 13, 2023

The Wagner Group: Status and Accountability

by Winston WilliamsJennifer Maddocks

February 23, 2023

The Law of Crowdsourced War: Democratized Supply Chains – Part I

by Gary Corn

March 1, 2023

Reprisals in International Law

by Michael N. Schmitt

March 6, 2023

The Law of Belligerent Occupation

by David A. Wallace 

March 8, 2023

Seizure of Russian State Assets: State Immunity and Countermeasures

by Daniel Franchini

March 8, 2023

The Law of Crowdsourced War: Democratized Supply Chains – Part II

by Gary Corn

March 15, 2023

“Damn the Torpedoes!”: Naval Mines in the Black Sea

by Ben RothchildMark Jessup

March 15, 2023

Landmines and the War In Ukraine

by Dario PronestiJeroen van den Boogaard

March 20, 2023

Russia’s “Re-Education” Camps: Grave Violations Against Children in Armed Conflict

by Alison Bisset

March 20, 2023

A Path Forward for Food Security in Armed Conflict


March 22, 2023