From Commitment to Action: The Next Steps in Holding Russia’s Leaders Accountable for the Crime of Aggression Against Ukraine

Key Takeaways

• STCA signed June 25 2025 by Ukraine and Council of Europe
• Estonia first to join EPA; 25‑30 states needed
• EU provides €10 million for Phase 0 advance team
• Tribunal will progress through advance, skeleton, then full operation

Pulse Analysis

The Special Tribunal for the Crime of Aggression against Ukraine (STCA) marks the first multilateral mechanism designed specifically to prosecute the war‑crime of aggression committed by Russian senior officials. Signed on 25 June 2025 by Ukraine and the Council of Europe, the treaty fills a jurisdictional gap that the International Criminal Court cannot address because Russia is not a party to the Rome Statute and a UN Security Council referral is unlikely. By anchoring the tribunal in customary international law, the STCA reinforces the prohibition on the use of force and signals that even the highest political leaders can be held accountable.

The accession process has already begun, with Estonia becoming the inaugural member of the Enlarged Partial Agreement (EPA) on 11 February. While the Council of Europe requires a minimum of 16 signatories, analysts estimate that 25‑30 states are needed to ensure political legitimacy and financial sustainability. The European Union has earmarked €10 million for Phase 0, the advance‑team stage that will draft institutional rules, security protocols, and locate premises in The Hague. Subsequent phases will build a skeleton tribunal and, ultimately, a fully operational court capable of issuing indictments and conducting trials, including in absentia.

Because the STCA will operate under intense geopolitical scrutiny, its phased rollout is intended to lock in commitment and reduce the risk of reversal. Each completed stage not only demonstrates operational capacity but also encourages additional states to join the EPA, strengthening donor confidence and deterrence against future aggression. By treating the crime of aggression as a prosecutable offense, the tribunal creates a strategic investment in global security, shifting the cost calculus from post‑conflict reconstruction to early legal accountability. Successful implementation could reshape the architecture of international criminal justice and set a precedent for addressing state‑initiated wars of aggression.