Using hammers, bulldozers and explosives, Islamic State militants can be seen smashing thousands of years of history in a purported ISIS video posted online earlier this week.

After standing for more than 3,000 years, the ancient Iraqi Assyrian city of Nimrud, including its priceless stone friezes and archaeological riches, appear to have fallen to the hands of militants and the ideology of ISIS.

Its just the latest historical site ravaged by the group, which now holds a third of Iraq and neighbouring Syria in its self-declared caliphate.

ISIS says the relics promote idolatry and violate Islamic law.

Clemens Reichel, Canadian archeologist and associate curator at the Royal Ontario Museum in Toronto, calls the destruction a cultural genocide.

"You can kill people on the ground, but if you destroy their heritage, you also kill their soul, and I just think that's something that we really need to come to terms with."

But not all of Reichel's contemporaries agree on what needs to be done in the face of the evisceration of UNESCO heritage sites in Iraq and Syria.

In fact, the fighting has re-ignited a battle among Western museum curators and archaeologists over whether museums should be returning antiquities to their countries of origin.

The push for repatriation

Decades ago, museums kept whatever they acquired even if it had been looted or bought from dubious sources. But that practice is now largely seen as shameful and colonialist.

Parthenon-Marbles-feature

Britain and Greece are currently locked in a battle over the Parthenon Marbles. Athens argues that the artefacts, which have been displayed in London's British Museum since 1816, were taken from Greece illegally and must be returned.

More recently, there has been a growing acceptance that artifacts should be repatriated to their countries of origin. 

That shift in thinking has seen the return of many historical artifacts, including the repatriation of a Turkish bust of Hercules, and the the return of Nazi-looted artworks to their rightful owners.

The idea is also central to a dispute between Britain and Greece over the Parthenon Marbles, which Athens maintains were illegally removed while the country was under Turkish occupation.

Preserving the past

James Cuno, an American art historian and curator, is an outspoken critic of repatriation. He believes that important artifacts should be considered the property of all humanity and shared across the globe.

"I'm concerned about preserving the past for the future and sharing that with the world," said Cuno, who currently serves as president of the J. Paul Getty Trust, which runs the Getty Museum and Getty Centre in California.

"It doesn't matter to me where they're preserved if they're preserved for the world."

Despite arguing that museums should be allowed reasonable ways to acquire undocumented antiquities, Cuno doesn't think the world's cultural riches should all be brought to Europe and North America.

In fact, he suggests that the more widely important pieces are distributed can help protect them from conflict in the long run. 

No museum is safe

"Calamity can happen anywhere" said Cuno in an interview from Los Angeles, "but it's not likely to happen everywhere simultaneously. So the more you distribute the risk the more likelihood there is that things will survive the calamity that necessarily will happen at some point."

Mideast Islamic State This Week

Militants take sledgehammers to an ancient artifact in the Ninevah Museum in Mosul, Iraq in an image distributed in February. (AP file photo)

But for Reichel, who has travelled to Iraq several times to assess the damage to artifacts caused by fighting and looting, the acquisition of goods from conflict zones by Western collectors and museums is far from simple.

"The minute that these events in Iraq started," says Reichel, "voices came about again saying that we should open up acquisition policies of museums, making it easier to purchase artifacts, just to get them out of the area of conflict."

"But what these people do not discuss,"  Reichel adds, "is that these artifacts that you can buy on the market now ... they have been looted."

Reichel argues, the goodwill of collectors can help stock the armouries of ISIS fighters.

He also points out that no museum in the world is safe. "World War II was a great example," said Reichel. "You had artifacts from the Middle East being brought to Europe, to Berlin in particular, and these museums were bombed in the war, and a lot of it was lost."

From the Islamic State to Nazi occupied Europe, one thing history makes clear is that the loss of art and cultural heritage is an ugly fact of conflict — whether looted from nations, individual collectors or the presumed safety of museums.

With files from Deana Sumanac-Johnson and The Associated Press