Russian President Vladimir Putin has decided to wage a winter war of attrition against Ukraine, targeting its civilian population in an attempt to starve and freeze the country into submission. In light of this dangerous escalation, the West must heed Ukrainian President Volodymyr Zelensky’s urgent plea for additional support.

To be sure, supplying the Ukrainian military with weapons beyond anti-tank and anti-aircraft missiles walks the fine line that US President Joe Biden and NATO drew between defensive assistance and active involvement. But the United Kingdom and the United States could help to pressure Russia by joining those countries who are calling for a special international tribunal to investigate and indict Putin and his entire Security Council for their war of aggression, as Ukraine has requested.

International human-rights lawyers have been pressing for a special tribunal to be established since the outset of the war in Ukraine. But the Dutch government’s recent announcement that it supports the creation of an interim prosecutor’s office and would be willing to host the tribunal, together with the European Union’s support for a specialized court to investigate and prosecute Russia’s invasion, represents a breakthrough. With the process of gathering evidence well underway, the US and the UK must back the effort to prosecute Putin and his accomplices for their crime of aggression.

The United Nations defines an act of aggression as the “invasion or attack by the armed forces of a state of the territory of another state, or any military occupation.” If a trial were to move forward, not just Putin but his entire inner circle would be in the dock.

Because Ukraine recognizes the crime of aggression in its legislation, a special international tribunal could try Putin under Ukrainian law without creating a precedent that could worry the US and other major powers. To that end, the Ukrainian parliament recently approved a resolution calling on the UN, the EU, and the Council of Europe to establish such a tribunal.

While European parliaments, the Council of Europe, and NATO have long supported the proposed investigation, they were recently joined by the foreign ministers of Estonia, Latvia, and Lithuania. Following Zelensky’s efforts to prepare the ground for a tribunal, international organizations have meticulously documented tens of thousands of criminal charges related to Russian military actions during the war.

Late last month, European Commission President Ursula von der Leyen outlined the case for establishing a new UN-backed court, saying that “Russia must pay for its horrific crimes, including for its crime of aggression against a sovereign state.” This month, the European Council invited other EU bodies to advance the investigation process, “stressing that the prosecution of the crime of aggression is of concern to the international community as a whole.”

As Karim Khan, the International Criminal Court’s chief prosecutor, recently pointed out, establishing a special court for Putin’s war crimes creates a risk of fragmentation, given that the ICC is already investigating Russia’s offenses against Ukraine. But while the ICC can investigate and prosecute war crimes and crimes against humanity, as well as genocide, it would likely need a long time to gather the evidence necessary to establish a direct legal connection between Russian leadership and atrocities on the ground.

But an even bigger issue is the ICC’s lack of jurisdiction. Ukraine and Russia have not ratified the ICC’s founding Rome Statute or the Kampala Amendments, which added the crime of aggression to the original treaty. Only a mandate from the UN Security Council could change this, but Russia’s veto power rules this out.

But Putin’s crime of aggression can and must be tried sooner rather than later. Setting up an internationalized court drawing on the domestic laws of Ukraine, Belarus, and Russia is the very least that Western powers can do to help Ukraine’s people. The international community should send brutal Russian aggressors a clear message: There will be no safe haven and no hiding place for anyone guilty of war crimes.

The world was slow to respond to Serbia’s aggression against Bosnia in the 1990s, enabling Serbian dictator Slobodan Milosevic to think that he could rape, ravage, mutilate, torture, and execute people with impunity. Eventually, the courts caught up with Milosevic, and he died in a prison cell while on trial. But it took over a decade and thousands of lost lives to hold him accountable.

If the UN General Assembly cannot support a special tribunal on Russia’s aggression, the EU and the Council of Europe should do so. And if prosecutors investigate Putin and his cabal over the next year, they could pursue indictments in absentia. This would guarantee an end to Russian officials’ ability to travel overseas without fearing arrest.

Whatever the outcome, it is high time that the world took the fight to Putin and his enablers. The UK and the US must act quickly, both for Ukraine’s sake and to honor the legacy of the post-World War II Nuremberg trials, when the free world stood its ground and ensured that war criminals were held accountable.

Gordon Brown

Gordon Brown, a former prime minister and chancellor of the exchequer of the United Kingdom, is United Nations special envoy for global education, chair of Education Cannot Wait’s high-level steering group, and chair of the International Commission on Financing Global Education Opportunity. -- Ed.

(Project Syndicate)