What are war crimes? The International Criminal Court (ICC), the world’s first permanent war crimes tribunal, defines them as “serious violations” of the Geneva Conventions, a set of humanitarian laws to be observed in war. Jonathan Hafetz, a professor of international criminal law and national security at Seton Hall University School of Law, told Reuters that the execution of civilians, as reported in Bucha, was a “major war crime”. Russia continues to deny guilt. The Defense Ministry insisted on Sunday that “not a single civilian has been subjected to violent action by the Russian army.” How can a case that shows war crimes be created? Jake Sullivan, a U.S. national security adviser, told reporters Monday that there are four main sources of evidence: information gathered by the United States and its allies, including intelligence sources. Ukraine’s own efforts on the ground to develop the case and document the homicide case; material from international organizations, including the United Nations and NGOs; and findings from independent global media through photographs, interviews and documentation. Can Putin be held personally responsible for the actions of his troops? The prosecution could argue that Putin and his inner circle committed war crimes by directly ordering an illegal attack or knowing that crimes were being committed and failing to prevent them. This hypothesis may be difficult to prove individually, but if it fits into a broader model throughout Ukraine, it becomes more compelling. The United States had accused Russia of war crimes even before Bucharest. Philippe Sands, a professor at University College London, told the Associated Press: “You have to prove that they knew or could have known or should have known. “There is a real danger that you will end up with trials of middle-class people in three years and the main culprits of this horror – Putin, Lavrov, Secretary of Defense, members of the secret services, military and financiers who support it – will come off.” Who would make such a trial? The ICC opened 20 years ago to prosecute perpetrators of genocide and crimes against humanity. However, the United States, China, Russia and Ukraine are not members of the tribunal, which has been criticized for focusing too much on Africa and enforcing “selective justice”. ICC Attorney General Karim Khan said in February that he had opened a war crimes investigation in response to the Russian invasion of Ukraine. Although it has not signed, Ukraine has previously approved an investigation dating back to 2013, which includes the annexation of Crimea by Russia. The ICC will issue arrest warrants if prosecutors can show “reasonable grounds” to believe war crimes have been committed. But Russia is unlikely to comply, and the ICC cannot prosecute anyone in absentia. The US reluctance to attend the trial is also diplomatically embarrassing and is likely to provoke cries of Western hypocrisy. “As far as America is concerned, the ICC has no jurisdiction, no legitimacy and no power,” Donald Trump once told the UN General Assembly. His government has announced that the United States will impose a visa ban on ICC officials involved in a possible American court investigation into alleged crimes in Afghanistan. However, Sullivan said on Monday: “The United States has in the past been able to cooperate with the International Criminal Court in other areas, even though it did not sign. “But there are several reasons why one might consider alternative venues.” What are these “alternative spaces”? The UN seems to be an obvious starting point. But one problem with going through the UN Security Council is that Russia is a permanent member. “It would be hard to imagine that they would not try to veto something,” Sullivan said. Another option may be a special court organized by a group of countries. The Nuremberg tribunal was set up by the United States, Britain, France and the Soviet Union to hold Nazi leaders accountable after World War II. Possible models for Ukraine could include tribunals set up to prosecute war crimes committed during the Balkan wars in the early 1990s and the Rwandan genocide in 1994. Another example was the UN-backed a special court for Sierra Leone, which was set up in 2002 to bring to justice those responsible for the atrocities committed during the country’s 1996 civil war. What about a different charge? It would be easier to prosecute Putin for the crime of aggression after waging an unprovoked war against another sovereign country. The ICC has no jurisdiction in Russia over the crime of the attack because Russia has not signed. Last month, dozens of prominent lawyers and politicians, including Ukrainian Foreign Minister Dmitry Kuleba and former British Prime Minister Gordon Brown, launched a campaign to set up a special tribunal to try Russia for the crime of attacking Ukraine. How long will a prosecution take? Probably many years. The International Criminal Tribunal for the former Yugoslavia (ICTY) indicted the first head of state, then-Yugoslav President Slobodan Milosevic, in 1999 and detained him in 2001. His trial began in 2002 and was ongoing when he died in The Hague in 2006. Charles Taylor, the former president of Liberia, has been found guilty of complicity in war crimes and crimes against humanity in support of guerrillas who committed atrocities after four years of hearings at the Sierra Leone Special Court in The Hague.