The crime of aggression: easy to prove, but (almost) never tried
Many have noted that the current President of the United States (“U.S.”) is actively undermining the international legal system that his country once helped to establish. A very clear demonstration of this was the United States’ recent aggression against Venezuela. This stands in stark contrast to the positive contributions made by the United Sates to the development of the international legal order, notably through the role of U.S. prosecutors at the Nuremberg trial who ensured that the crime of aggression is recognized as an international crime. The crime of aggression engages the criminal responsibility of the political leaders who commit acts of aggression.
While national and international courts have convicted individuals for war crimes, crimes against humanity, andgenocide, no one has yet been prosecuted for the crime of aggression. Whilst the U.S. president openly claims that the acts of aggression are legitimate, the Council of Europe—backed by nearly forty European and allied states in 2025—is working to establish a special international court for those responsible for the aggression against Ukraine. Some may view this as evidence of an ongoing double standard.
A new European tribunal on the crime of aggression
A bilateral agreement was signed in 2025 between Ukraine and the Council of Europe providing for the creation of a Special Tribunal for the Crime of Aggression. The statute of this tribunal specifies that immunities, including those attached to the office of head of state, do not constitute an obstacle to prosecution, and that a trial in the absence of the accused is possible under certain conditions. According to some sources, the Council of Europe’s Committee of Ministers was due to meet in January in order to accelerate the operational launch of this Tribunal. Ironically, in the same month, the leader of the Venezuelan opposition symbolically handed Donald Trump her Nobel Peace Prize medal for the U.S. military operation conducted in Venezuela.
Whatever one’s assessment is regarding the nature of Nicolás Maduro’s regime and the allegations of crimes against humanity committed by that dictatorship, the use of armed force by one state against the territorial integrity of another violates the UN Charter and amounts to an act of aggression in the absence of self-defence, authorization by the United Nations Security Council, or the consent of the state concerned.
The gravity of the crime of aggression is continually reaffirmed
The gravity of this crime has been continually reaffirmed. Regarding state responsibility, the United Nations International Law Commission characterized aggression in 2001 as a serious breach of an obligation arising from a peremptory norm of international law. As for individual criminal responsibility, the International Criminal Court (ICC) has had jurisdiction since 2018, under certain conditions, to try leaders—including heads of state—who ordered the commission of a crime of aggression. However, the ICC’s jurisdictional restrictions prevent any prosecution of the U.S. president for the aggression against Venezuela, just as they prevent prosecution of the Russian president for the aggression against Ukraine—hence Europe’s desire to create an ad hoc tribunal intended in particular to try Vladimir Putin for this crime.
From an evidentiary standpoint, prosecuting Vladimir Putin for aggression against Ukraine would present an unusually strong case for prosecutors, as direct responsibility for such international crimes is rarely easy to prove, especially for a head of state.
It is one of the reasons why the ICC—competent only for war crimes and crimes against humanity committed in Ukraine—is currently prosecuting Vladimir Putin only for a very specific category of offences, namely child abductions for which there are documents signed by him. However, the situation is entirely different with regard to the crime of aggression as Vladimir Putin, like Donald Trump in the case of Venezuela, has publicly claimed ownership of the acts, leaving his fingerprints on all the constituent elements of the offence.
The question of double standards and of priorities
Even if this crime is particularly serious under international law and relatively simple to demonstrate in court, given that George W. Bush was never prosecuted for the 2003 aggression in Iraq and Donald Trump will very likely never be prosecuted for aggression against Venezuela in 2025, should a new tribunal nevertheless be created and substantial resources devoted to prosecuting Vladimir Putin for aggression? It can be noted that a Register of Damage for Ukraine was also established in 2023 by the Council of Europe, to document claims for damages, losses and injuries caused by Russian aggression. As of January 2026, 100,000 claims have been submitted.
The issue of double standards inevitably arises in the context of international crimes, as the majority of such offenses go unprosecuted. For instance, while it is unlikely that Kim Jong-Un will ever be tried for the many alleged crimes committed against North Korea’s population, this need not delegitimize the proceedings brought before the ICC against former Philippine president Rodrigo Duterte. This logic can also be applied to the crime of aggression. In a situation where the United States has reportedly considered using force against a territory linked to a European state, a legal precedent that would be established by trying Mr Putin in The Hague for aggression against Ukraine could be particularly impactful.
In Europe, the key issue is setting priorities. With ICC employees facing U.S. sanctions, urgent action should focus on protecting and strengthening this institution, which has existed for almost twenty-five years. This includes, in particular, enforcing—finally!—the European “blocking statute”, designed precisely to protect European citizens and institutions from the effects of sanctions imposed by third countries.
Doing more for international law is always desirable. But in these perilous times, defending and strengthening what already exists must be the absolute priority.
The article first appeared in French on Le Temps on the 2nd of February 2026
Image: On June 25, 2025, President Volodymyr Zelenskyy and Secretary General of the Council of Europe Alain Berset signed an agreement in Strasbourg to establish a Special Tribunal for Russia’s crime of aggression against Ukraine © Prosecutor General’s Office
