Podcast Summary

The Crime of War: From the Nuremberg Trial to Ukraine

London School of Economics and Political Science Public Lectures and Events Podcast
Date: October 7, 2025
Host: Professor Gary Simpson (LSE)
Guest Speaker: Professor Klaus Kress (University of Cologne, ICC Special Advisor on Aggression, speaking in personal capacity)

Overview

This episode explores the evolving concept of the "crime of aggression" from its origins in the Nuremberg Trials to its current application in the context of Russia’s invasion of Ukraine. Professor Klaus Kress delivers a detailed review of historic challenges, legal developments, and political controversies around the criminalization of war-making, focusing on recent efforts to create a dedicated Special Tribunal for Russian acts of aggression and parallel attempts to reform the International Criminal Court (ICC) statute. The event includes a substantive Q&A delving into philosophical, legal, and practical obstacles to enforcing international law against leaders accused of aggressive war.

Key Discussion Points and Insights

1. Historical Context: The Legacy of Nuremberg (16:00–28:00)

• Nuremberg as Precedent: The crime of aggression (then "crimes against peace") was established after WWII in the London Agreement of 1945, with decisive contributions from Soviet legal advisor Aron Trainin.
• Nuremberg Promise: Chief US prosecutor Robert Jackson’s vision: “the law includes, and if it is to serve a useful purpose, it must condemn aggression by other nations, including those who sit here now in judgment.” (45:10, quoted by Kress)

2. Aggression and Ukraine—A Revival (28:00–37:00)

• Philip Sands’ Essay as a Catalyst: An influential 2022 Financial Times essay argued for a dedicated tribunal to try Putin for aggression, invoking the Nuremberg legacy. Ukraine’s diplomats rapidly took up this idea.
• ICC’s Limits: The ICC Prosecutor stated in February 2022 that legal strictures prevented prosecuting Russian leaders for aggression due to jurisdictional constraints—unlike for war crimes or genocide.

“The ICC’s scope of action with respect to the crime of aggression is curtailed by particularly stringent conditions, far more stringent than those applying to the other three crimes...”
—Professor Kress (07:20)

3. The Path to a Special Tribunal (37:00–50:00)

• Diplomatic Developments: Intensive international negotiations led to the likely creation of a Special Tribunal for Aggression Against Ukraine, anchored in an agreement between Ukraine and the Council of Europe.
• Design Compromise:
  • G7 powers pushed for the tribunal to be legally rooted in Ukraine’s system, with international participation.
  • Ukraine and supportive mid-sized states demanded a fully international tribunal with universal reach.
  • The outcome: a hybrid, regionally anchored but international tribunal—jurisdiction based on Ukraine’s territory, trigger via national prosecutor, but applying the ICC’s crime of aggression definition (Article 8bis).
  • The tricky question of immunity for Russian leaders was resolved so an indictment could be prepared but not pursued while a target (e.g., Putin) remains in office.

“The jurisdiction of this Tribunal is based on Ukraine’s territorial jurisdiction...proceedings will have to go through a national trigger... The personal immunities of the Russian troika...are basically maintained.”
—Professor Kress (47:00)

4. The ICC Statute Reform Debate (50:00–56:00)

• Calls for Universal Applicability: Concerns that only prosecuting Russian aggression could create a double standard (“is this to be...an isolated incidence...or is this the beginning of more?”).
• Harmonization Proposal: A majority coalition of states (notably from Europe, Africa, and Latin America) pushed to remove the ICC’s current restrictions on prosecuting aggression, seeking equality with other core crimes.
• Opposition: A minority, led by Western states (Canada, France, Japan, New Zealand, UK) and supported by the US as observer, cited legal/technical concerns and threatened sanctions.

“The minority...uttered the threat to impose further sanctions on the ICC should this reform proposal be adopted.”
—Professor Kress (54:40)

5. Where We Stand Now (56:00–64:40)

• Consensus Resolution: While not fully adopting reform, the Assembly of States Parties agreed to keep the issue on the agenda and committed “to the aim of strengthening the Court’s jurisdiction over the crime of aggression,” with negotiations set to continue toward 2029.
• Kress’s Assessment: The marginalization of aggression as an international crime is ending, but universal legal accountability remains an unfulfilled Nuremberg promise—progress is real but slow and compromise-driven.

“The long-term marginalization of the crime of aggression is over...but the Nuremberg promise...will remain unfulfilled, at least for the next four years to come.”
—Professor Kress (65:50)

Notable Quotes and Memorable Moments

• Ambassador Mayet Bahima, Palestine (via Kress, 65:50):
  “When we talk about the crime of aggression, we are looking at a hurdles race where instead of running we continue to walk and where obstacles continue mounting and the victims...are asked to wait…”

• On Difficulties with Universalization (73:15):
  “Is it really true that we do not have to face these problems with respect to other crimes?... There is a suspicion that the sensitivity with regard to a degree of uncertainty is greater when it comes to [Western] personnel than for genocide or crimes against humanity...”
  —Professor Kress

Audience Q&A and Panel Discussion Highlights

Q1: Can international criminal law escape ‘just war’ arguments? (57:47)

• Kress emphasizes that the legal definition of aggression requires violations of the UN Charter to be "manifest," thereby steering clear of controversial cases (e.g., humanitarian intervention) and upholding legal certainty.
• “The word manifest... encapsulates the entire exchange between states about... controversial cases." (61:40)

Q2: Could US sanctions on the ICC be criminalized as ‘obstruction of justice’? (58:40)

• Kress agrees that US sanctions blocking ICC officials raise “serious questions of criminality under the so-called annex crimes...obstruction of justice.” (80:30)

Q3: Is the Special Tribunal enforceable in practice? (59:31)

• Kress candidly says prosecution will be impossible so long as Russian leaders remain in power, but indictment and investigation are vital first steps for long-term accountability:

“This is a long-term project... All those steps are important steps to signal that we are not simply fatalistic with respect to fundamental violations...” (82:20)

Q4: Does the tribunal’s international or regional nature affect immunity? (72:24)

• Kress notes only international tribunals with a "credible universal orientation" can set aside personal immunities.

Q5: Does customary law pre-date the UN Charter on aggression? (76:55)

• He asserts the crime of aggression as a serious international offense crystallized only at Nuremberg; interwar treaties like the Kellogg-Briand Pact did not explicitly criminalize it.

Timestamps for Key Segments

• Historical Introduction / Nuremberg: 16:00 – 28:00
• Post-2022 Developments (Ukraine, Philip Sands, ICC Limits): 28:00 – 37:00
• Negotiating the Special Tribunal: 37:00 – 50:00
• ICC Statute Reform Debate: 50:00 – 56:00
• Where We Are Now, Kress’s Summary: 56:00 – 65:50
• Q&A – Just War and Law: 57:47 – 61:40
• Q&A – Sanctions / Enforcement / Immunity: 58:29 – 84:00

Tone and Speaker Attributions

• Prof. Klaus Kress: Precise, reflective, occasionally wry; balances legal-analytic rigor with a realist appreciation for the limits and politics of international justice.
• Prof. Gary Simpson: Probing, occasionally skeptical about universalist ambitions in international criminal law, but appreciative of Kress’s expertise.
• Audience and Online Participants: Challenging, insightful questions on law, philosophy, and practicality.
• Quotations: See “Notable Quotes” above for highlighted moments with attributions and timestamps.

Concluding Reflection

The episode provides a deeply informed and balanced overview of how the legal and political architectures for prosecuting war crimes—specifically aggression—have changed and how much remains to be done. Kress’s analysis reveals both the challenges of securing universal legal accountability and the resilience and creativity of international legal diplomacy.

“We have an obligation of results when it comes to the issue of the crime of aggression.”
—Ambassador Bahima, quoted by Kress (65:50)

For listeners seeking to understand the real-world development, debate, and prospects of prosecuting leaders for the crime of aggression—from Nuremberg to the war in Ukraine—this episode combines historical context, legal insight, and lively debate among the world’s foremost experts in the field.