What is the special tribunal for Ukraine that world leaders have backed?

KYIV, Ukraine (AP) - Some 40 world leaders announced their support Friday for the creation of a new international court to prosecute those most responsible for Russia’s full-scale invasion of Ukraine.

The special tribunal aims to target senior Russian leaders for the "crime of aggression,” which underpins the countless war crimes Ukraine accuses Russian forces of committing since the start of the war in 2022.

Because Russia is not a member of the International Criminal Court, it cannot prosecute Russian President Vladimir Putin and other senior leaders for starting the conflict. Ukrainian and European leaders came up with the special tribunal as an alternative way to hold Russian leaders to account.

The court will be formed following a joint agreement between Ukraine and the Council of Europe, the continent’s top human rights organization.

Since early in the conflict, Kyiv has been pushing for the creation of a special tribunal that goes beyond prosecuting war crimes that Ukraine alleged Russian forces committed - including bombing civilian infrastructure, killing civilians, rape, taking hostages and torture. Russia denies those claims.

"If we want true justice, we should not look for excuses and should not refer to the shortcomings of the current international law but make bold decisions that will correct those shortcomings that unfortunately exist in international law," Ukrainian President Volodymyr Zelenskyy said during a visit to the Netherlands in 2023.

Similar special tribunals were established after World War II, the Balkan wars sparked by the disintegration of the former Yugoslavia and the 1994 Rwandan genocide.

The institution will be funded by the countries who back it, known as the Core Group, including the Netherlands, Japan and Canada. The United States had backed the projected under former President Joe Biden, but President Donald Trump’s administration did not support the initiative.

The legal framework for the project was agreed on by leaders in February.

The crime of aggression is the planning and execution of a large-scale military invasion of another country.

"The crime of aggression is sometimes referred to as the 'mother of all other crimes' because it precedes all of the other crimes, war crimes, crimes against humanity, even genocide,” Iva Vukusic, an international law expert at the University of Utrecht, told The Associated Press.

"You don't prosecute foot soldiers for aggression," she added. The tribunal plans to pursue cases against around 20 to 30 high-ranking officials.

A dozen Nazi leaders including Hermann Göring and Rudolf Hess were convicted of what was then called "a crime against peace" during the Nuremberg trials following WWII. That was the last time anyone has been convicted of aggression.

International law grants the so-called troika - consisting of a country's head of state, head of government and foreign affairs minister - immunity from prosecution while they are in office.

However, the tribunal could initiate proceedings against Putin and wait until he leaves office to move forward with a trial. There is no statute of limitation on the crime of aggression.

The court will have the power to hold trials in absentia, though anyone convicted without being in the custody of the tribunal would have the right to a retrial.

The move to create a special tribunal aims to fill a void created by limitations on the ICC. While The Hague-based court can go after Russian nationals for genocide, war crimes and crimes against humanity, it cannot prosecute Russians for orchestrating the invasion itself.

The 2002 Rome Statute which created the court was amended in 2010 to include the crime of aggression - but only for countries that have joined the court. The Russian Federation is not a member state.

The court has issued an arrest warrant for Putin for war crimes, accusing him of personal responsibility for the abductions of children from Ukraine, as well as five other officials.

The Hague, already home to the ICC, the top court of the United Nations and other judicial institutions, has been suggested as a location but a final decision has not yet been made.

The city is already home to the International Center for Prosecution of the Crime of Aggression, which supports evidence-gathering and is overseen by the European Union's judicial cooperation agency, Eurojust. The Council of Europe-backed register of damages, which allows Ukrainian victims of war to catalog the financial harm they have suffered, is also based in the Netherlands.

Backers are hopeful the institution will be up and running by early next year.