War crimes happen whenever there is war, but seldom have they been investigated in real time and within weeks of the outbreak of hostilities, as is happening with Russia's invasion of Ukraine.
After a brief initial hesitation to publicly brand the architects of the Ukraine invasion as war criminals, the United States and its European allies began issuing explicit statements about what they were seeing before the war was one month old.
"We've seen numerous credible reports of indiscriminate attacks and attacks deliberately targeting civilians, as well as other atrocities," U.S. Secretary of State Antony Blinken said last week.
"Russia's forces have destroyed apartment buildings, schools, hospitals, critical infrastructure, civilian vehicles, shopping centers and ambulances, leaving thousands of innocent civilians killed or wounded."
Normally, investigations into such allegations take place after the guns go silent so that investigators can inspect war-torn regions, document evidence, talk to victims and substantiate crimes.
But in the case of Ukraine, even the normally cautious International Criminal Court has been moved to action within the first week. "I have decided to proceed with opening an investigation," ICC prosecutor Karim A.A. Khan announced on February 28.
Khan's probe into possible Russian war crimes in Ukraine must be authorized by the ICC's Pre-Trial Chamber, and there appear to be many legal and political obstacles in the way.
In July 1998, more than 100 countries signed the so-called Rome Statute, creating an international judicial institution that would investigate war crimes and crimes against humanity internationally. It would also prosecute individuals responsible for such crimes.
Since it began operations in July 2002, the ICC has handled 30 cases, resulting in 10 convictions, 35 arrest warrants and four acquittals. From those convictions, 17 individuals have been incarcerated at an ICC detention center in the Netherlands.
Only an ICC member state, of which there are 123, can refer a case to the court for investigation and prosecution.
Ukraine is not a member. Neither is the U.S., Russia or China.
However, Ukraine has accepted ICC's jurisdiction to investigate alleged war crimes on its territory.
"The ICC is a court of last resort," said Jamil Dakwar, director of the human rights program at the American Civil Liberties Union. He told VOA that the court acts after it has determined that the country where the crimes were perpetrated is unable or unwilling to investigate and prosecute war criminals.
U.S. laws even limit the ways the U.S. can support ICC investigations, according to Alex Whiting, a visiting professor at Harvard Law School.
"The U.S. has actually taken the position that there are different ways to hold alleged Russian perpetrators to account, citing Ukrainian law and the possibility of prosecutions under that law, prosecutions by third states with jurisdiction, and then finally the ICC," Whiting told VOA.
U.S. President Joe Biden has called his Russian counterpart "a war criminal" who should not "remain in power."
As of now, the ICC has 17 open investigations, mostly in Africa and Asia. The U.S. government has strongly opposed two ICC investigations — in Afghanistan and in the Palestinian territories.
In Afghanistan, a state member of the ICC, the U.S. conducted its longest foreign war for about two decades. The ICC has a long list of crimes allegedly committed by warring parties, including U.S. forces and Taliban fighters, against Afghan civilians from 2003 onward.
The U.S. government, under former President Donald Trump, went as far as to impose sanctions on an ICC prosecutor, Fatou Bensouda.
Successive U.S. administrations have also objected to the ICC's probing of alleged crimes committed by Israeli forces against Palestinians.
"I think the U.S. is still seen as hypocritical in the way that it's engaging with the ICC, because it says as long as the ICC is not addressing or not dealing with accountability for our own conduct, we will be fine with that," said the ACLU's Dakwar.
He said that policy has undermined the ICC. "Either you are on the side of international justice, or you are on the other side," Dakwar added.
The Biden administration has lifted the sanctions on the ICC prosecutor tasked to investigate the Afghanistan case, but the U.S. government says it still disagrees "strongly with the ICC's actions relating to the Afghanistan and Palestinian situations."
Dakwar said the U.S. "is really standing at a juncture here because it has to decide on which side of history or which side of international justice it wants to be."
Lea Brilmayer, a professor of law at Yale University, told VOA there is no way to bring Russia into the criminal court. "It's wishful thought by politicians when they say Russia should be held accountable for the war crimes in Ukraine," she said.
In general, she said, only defeated leaders face trials, such as the Nazi generals and politicians who were tried in Nuremberg after World War II. But Russia is unlikely to face the fate of Hitler's Germany.
While waging the war in Ukraine, Russian officials have held talks with representatives from Ukraine and other countries.
Some experts see the accusations of war crimes against Russian President Vladimir Putin as political rhetoric and a possible bargaining chip in future peace talks, rather than a viable effort to bring the Russians before any legal forum.
They note that in the brief history of the ICC, no world power has yet been investigated and tried for the wars it has conducted or sponsored in other countries.