EVERY few moments the thump of an explosion reverberated from somewhere not so far away. These were the last days of intense fighting north of Kyiv and soon the Russian forces would be pulling back.

But in their wake, they seemed ­determined to leave as much death and destruction behind as possible and in the northern Kyiv suburb of Podil, Russian shelling had already left its ugly mark on the civilian population.

Over the previous few days, the force of the explosions had obliterated one ­structure in Podil’s shopping centre car park and gutted an adjacent ­10-storey building, shattering windows in the ­surrounding residential tower blocks.

In one neighbourhood, charred and blackened trees and the mangled remains of cars sat alongside a huge crater gouged out of the ground by the impact of the shells and rockets that had landed.

In every block the windows had been blown out and the gable end of one had been sliced away exposing the insides of what had until recently been people’s homes.

The National: A block of flats blown wide open by Russian shells and rocket attacks in Kyiv’s northern Podil neighbourhood. Picture: David PrattA block of flats blown wide open by Russian shells and rocket attacks in Kyiv’s northern Podil neighbourhood. Picture: David Pratt

Wandering among the rubble I momentarily caught a glimpse of one elderly man who had returned to the bomb blasted ruin of his flat to pick up a few remaining belongings.

It was a forlorn task, but then for the people of this neighbourhood in Podil just like countless others across Ukraine, picking up the pieces of their lives will be an altogether greater challenge.

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All wars take a terrible toll on the ­civilian population and Ukraine right now is no exception. Just like the last major war in Europe in the former Yugoslavia, this conflict too appears to being fought seemingly without respect for the rules of warfare that were drafted in the wake of the Second World War and the Holocaust.

After the horrors of that global conflict prosecutors laying the groundwork for the Nuremberg trials devised the concept of crimes against humanity to protect people against systematic attack.

These codes of conduct put in place ­after 1945 were an effort to prevent a ­repetition of the worst abuses of the ­Second World War. They were, as authors Roy Gutman and David Rieff explained in their seminal book Crimes Of War: What the Public Should Know, designed to establish even in conflict, “a firebreak between civilisation and barbarism”.

The National: An exhausted child and mother at the Ukrainian-Polish border. Photograph: David PrattAn exhausted child and mother at the Ukrainian-Polish border. Photograph: David Pratt

But in the days following my visit to Podil, which itself has arguably been ­subjected to a war crime under ­international law, far worse horrors have surfaced in the Ukrainian towns of Bucha and Borodianka.

On Friday as rain fell, forensic ­investigators, clad in white suits, ­began ­exhuming a mass grave in Bucha, ­wrapping in black plastic bags and ­laying out the bodies of civilians who officials say were killed while Russian troops ­occupied the town just northwest of Kyiv.

Ruslan Kravchenko, from the ­prosecutor’s office in Bucha, said they had ­exhumed 20 bodies, 18 of whom had firearms and shrapnel wounds. He said two women had been identified, one of whom had worked at a supermarket in the town centre.

Since Russian troops pulled back from Bucha last week, Ukrainian officials ­report that hundreds of civilians have been found dead. Bucha’s mayor says ­dozens were the victims of extra-judicial killings carried out by Russian troops.

Speaking to Reuters news agency ­Bucha’s deputy mayor, Taras ­Shapravskyi, said more than 360 civilians were killed and around 260-280 were buried by other residents in a mass grave. He added that there were two parallel trenches dug at the mass grave site, with bodies piled on top of each other in layers.

For its part, the Kremlin has ­insisted that allegations of Russian forces ­executing civilians in Bucha are a ­“monstrous forgery” aimed at denigrating the Russian army.

Russia’s UN Ambassador Vassily Nebenzia told the Security Council last week that accusations of abuse were lies. He said that while Bucha was ­under ­Russian control “not a single civilian ­suffered from any kind of violence”.

The National: An elderly woman who has been sheltering in Kyiv metro since the start of the war and whose house has been destroyed. Photograph: David PrattAn elderly woman who has been sheltering in Kyiv metro since the start of the war and whose house has been destroyed. Photograph: David Pratt

Russia’s defence ministry also issued a statement saying that all photographs and videos published by the Ukrainian authorities alleging “crimes” by Russian troops in Bucha were a “provocation.”

Moscow has even gone as far as to ­accuse the Ukrainians of staging “fake” killings and hiring actors to play victims, even though satellite pictures showed corpses strewn on Bucha’s streets when the Russians still controlled the town of more than 40,000 people.

But with every day that passes ­Russia’s protestations have an increasingly ­hollow ring to them as further evidence of ­atrocities continues to mount.

Just a few days after the discovery of ­evidence pointing to the unlawful killing of civilians in Bucha, ­Ukrainian ­President Volodymyr Zelenskyy ­described the ­situation in nearby ­Borodianka as ­“significantly more dreadful”, and warned that more atrocities will likely unfold once full access is gained to ­cities and communities some which are still ­besieged by Russian forces.

“And what will happen when the world learns the whole truth about what the Russian military did in Mariupol?” Zelenskyy asked. “There, on almost every street, is what the world saw in Bucha and other towns in the Kyiv region after the withdrawal of Russian troops,” the ­president predicted of the southern port city that has been subjected to some of the heaviest fighting and bombardment.

Zelenskyy has already openly accused Russia of war crimes and “genocide” – the gravest of crimes against humanity – and said he had approved the creation of a “special mechanism of justice” under which Ukrainian and international investigators, prosecutors and judges will work together to lay the groundwork for a future war crimes tribunal.

The National: Volodymyr Zelenskyy has said Russia's war crimes are the worst seen since the Second World WarVolodymyr Zelenskyy has said Russia's war crimes are the worst seen since the Second World War

Doubtless the work of such investigators will also focus on Borodianka, a ­satellite town some 37 miles northwest of Kyiv where few buildings remain ­standing. These past days families there could be seen looking for relatives and watching diggers search through the ­rubble of an apartment block. Most of the building was charred and its middle ­section had been razed to the ground, leaving a gaping hole.

World leaders it seems are in no doubt who is to blame. US president Joe Biden has already described his Russian ­counterpart Vladimir Putin as a “war criminal” and said he should face trial.

In France President Emmanuel ­Macron, said there were “very clear ­indications of war crimes” in Bucha, and those ­responsible should answer for them. ­German chancellor Olaf Scholz ­meanwhile deplored the “terrible and grisly” images and said: “We must ­unsparingly investigate these crimes of the Russian military.”

Throwing accusations at Russia and its leaders however is one thing, but ­proving guilt over war crimes and holding to ­account those responsible is something else again.

For many of us looking on at the ­grisly photographs and television ­footage ­coming out of Ukraine right now it’s ­probably hard to understand what ­exactly constitutes war crimes amid such ­carnage.

According to the 1949 Geneva ­Conventions, war crimes encompass a range of behaviours in armed conflict. These include the intentional ­targeting of civilians, torture, or inhumane ­treatment, attacking areas that are not part of ­military objectives and ­intentionally ­attacking schools, hospitals, and ­religious ­buildings. The International ­Criminal Court defines war crimes as “grave breaches” of these conventions, which were ratified by all United Nations ­member states.

War crimes generally refer to ­“excessive destruction, suffering and civilian ­casualties”, while “rape, torture, forced displacement and other actions may also constitute war crimes”, says human rights and international law scholar Shelley ­Inglis who has written about war crimes in Ukraine recently for the online media outlet The Conversation.

Travelling across Ukraine recently and given such definitions of what ­constitutes war crimes, I, like many other ­eyewitnesses, am in little doubt that such offences have been committed. Perhaps the best single indicator of a major war crime is often a massive displacement of civilians and in that regard certainly vast numbers of ordinary Ukrainians have been forced to move and leave their homes.

The National: An exhausted child and mother at the Ukrainian-Polish border. Photograph: David PrattAn exhausted child and mother at the Ukrainian-Polish border. Photograph: David Pratt

At railway stations in Lviv, and on the Polish border, on the highways and ­backroads an endless stream of ­humanity is to be found either fleeing for their lives from the scene of a crime or the ­immediate threat of crimes at the hands of Russian forces.

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In the deep subterranean confines of the Kyiv metro, I found people who had sheltered there since the start of the war which is now over six weeks long.

Many had no homes to return to ­having been destroyed by the random shelling and rocketing of residential districts. All these people in terms of international law could be designated as victims of war crimes.

The National: Displaced Ukrainians have sheltered in the Kyiv metro from the start of the war and have no homes to return to. Photograph: David PrattDisplaced Ukrainians have sheltered in the Kyiv metro from the start of the war and have no homes to return to. Photograph: David Pratt

In the northern Kyiv neighbourhood of Podil I spoke with one man who was helping friends pack up their belongings before driving them out of Kyiv to a safer place. Even if they were to return right now as the threat against the capital ­recedes, the homes they left behind are uninhabitable ruins.

Which brings us to the question of ­accountability for such war crimes. Is it ever likely that those who gunned down civilians in the streets of Bucha, dumped corpses into wells with bags over their heads, tortured and raped, or unleashed barrages of shells on homes in ­Borodianka, Mariupol or Podil will ever be brought to justice?

There are several ways that countries and individuals can be made to answer for war crimes. The International Criminal Court (ICC), established in 2002 in The Hague, Netherlands, was set up to investigate and prosecute war crimes, genocide, crimes against humanity and crimes of aggression.

Its chief prosecutor, Karim Khan, took the unusual step of visiting ­western Ukraine briefly in March, where he held a video conference with President ­Zelenskyy. But neither the US, Russia nor Ukraine are parties to the agreement that set up the ICC.

The National: A screen in Kyiv metro shows Ukrainian president Volodymyr Zelenskyy giving a TV address to the nation. Photograph: David PrattA screen in Kyiv metro shows Ukrainian president Volodymyr Zelenskyy giving a TV address to the nation. Photograph: David Pratt

In addition to the ICC, though, the UN has in the past set up special tribunals to prosecute war crimes, as it did after the Balkan conflict in the 1990s.

Any future war tribunal might, ­alongside atrocities carried out by ­invading Russian forces and their civilian leaders, also be expected to investigate ­reports of alleged crimes by Ukrainian soldiers during the war.

But all of this should it ever eventually come about, is a long way off yet. While the immediate threat to Kyiv might have diminished for now, Russia’s promised ­intensification in Ukraine’s eastern ­Donbas region has all eyes focused on how the war there will now play out.

If one thing is certain it’s that many more alleged war crimes are sure to ­surface in the bitter fight for this part of the country that Putin dearly wants to seize control of and Zelenskyy will be ­under pressure to defend at all costs.

While an array of international ­judicial institutions has jurisdiction over ­abuses that Putin’s military is accused of ­carrying out in Ukraine, those courts ­differ in how they work and how their rulings are ­enforced. Few ultimately have any ­leverage over Russia.

“The concern I have is that we fast ­forward three years and there are half a dozen or so trials for mid-level ­commanders in The Hague for people who did things at Bucha, but the rest of the people like Putin and his military and defence leaders are unscathed,” observed Philippe Sands, director of the Centre on International Courts and Tribunals speaking to the Financial times a few days ago. “That would be a deplorable outcome,” he added.

Deplorable indeed, and of little ­consolation to those Ukrainians already the victims of crimes again humanity. Those like the women and children I saw last week at Warsaw railway station in Poland having earlier crossed the border from Ukraine that day.

Standing on the platform in the ­darkness and sub-zero temperatures amid snow flurries and a biting wind, I watched as an endless tide of ­grandmothers and ­mothers, their offspring in tow and ­struggling with baggage stepped into what for many was an unknown city and future.

How terrifying must it be to leave ­everything behind including fathers, ­husbands, sons, and step into an ­unfamiliar city in the dead of night with nowhere to stay and unsure of what ­tomorrow will bring?

Every one of these people forcibly ­displaced is a victim of war crimes ­perpetrated by Russia. But don’t hold your breath waiting to see Vladimir Putin or any other top Kremlin officials in the dock at The Hague any time soon.