Throughout his presidency, President Donald Trump has repeatedly attempted to distinguish between the “wonderful Iranian people” and their “hostile”, “brutal and corrupt” leadership.

But as he suggested the possibility of retaliatory strikes against Iran on Saturday, he resorted to a threat that – in other, prior conflicts – has deliberately blurred the distinction between countries' regimes and their people.

By suggesting strikes on “52 Iranian sites”, including some that are important to “the Iranian culture” rather than its military, Mr Trump threatened a way of waging war that has drawn growing outrage in recent decades, critics argued Monday.

Such attacks have been condemned as “cultural cleansing” by the former director general of UNESCO, Irina Bokova. “The deliberate destruction of heritage is a war crime,” she told the UN Security Council in 2017, adding that “it has become a tactic of war to tear societies over the long term”.

Ms Bokova was primarily referring to the destruction of cultural sites by militant groups at the time, but to some, her words now appear eerily relevant for Iran, which hosts 22 cultural UNESCO World Heritage Sites, including the ancient ruins of Persepolis with its palatial buildings and terraces.

US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Show all 35 1 /35 US airstrike kills Iran's Qassem Soleimani: Fallout in pictures US airstrike kills Iran's Qassem Soleimani: Fallout in pictures This photo released by the Iraqi Prime Minister Press Office shows a burning vehicle at the Baghdad International Airport following an airstrike in Baghdad, Iraq, early Friday 3 January AP US airstrike kills Iran's Qassem Soleimani: Fallout in pictures The wreckage of the car in which general Soleimani was travelling when a targeted US airstrike struck outside Baghdad International Airport on 3 January Ahmad Al Mukhtar via Reuters US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Demonstrators burn the US and British flags during a protest in Tehran after general Soleimani was killed in a targeted airstrike by American forces Reuters US airstrike kills Iran's Qassem Soleimani: Fallout in pictures A burning vehicle at the Baghdad International Airport following an airstrike. The Pentagon said Thursday that the US military has killed general Qassem Soleimani, the head of Iran's elite Quds Force, at the direction of Donald Trump AP US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Protesters burn Israeli and US flags as thousands of Iranians take to the streets to mourn the death of general Soleimani at the hands of America EPA US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Supporters of Donald Trump pray at an 'Evangelicals for Trump' campaign event held on the day following the killing of general Soleimani. At the event, the president praised the "flawless strike that eliminated the terrorist ringleader" AFP via Getty US airstrike kills Iran's Qassem Soleimani: Fallout in pictures A huge procession of mourners gather in Baghdad for the funeral of general Soleimani on 4 January AP US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Thousands of Iranians take to the streets to mourn the death of Soleimani during an anti-US demonstration to condemn the killing of Soleimani, after Friday prayers in Tehran, Iran EPA US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Iraqis perform a mourning prayer for slain major general Qasem Soleimani of the Iranian Revolutionary Guards at the Great Mosque of Kufa AFP via Getty US airstrike kills Iran's Qassem Soleimani: Fallout in pictures A billboard reading 'Death to America and Israel', installed by Iran-backed shiite armed groups at a street in Jadriyah district in Baghdad, Iraq EPA US airstrike kills Iran's Qassem Soleimani: Fallout in pictures A handout picture provided by the office of Iran's supreme leader Ayatollah Ali Khamenei shows him visiting the family of Soleiman KHAMENEI.IR/AFP via Getty US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Thousands of Iranians take to the streets in Tehran EPA US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Pakistani Shiite Muslims burn a mock of a US flag as they hold pictures of General Qasem Soleimani during a protest against the USA, outside the US Consulate in Lahore, Pakistan EPA US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Iran's Ambassador to Lebanon Mohammed Jalal Feiruznia, looks to a portrait of Soleimani, as he receives condolences at the Iranian embassy, in Beirut, Lebanon AP US airstrike kills Iran's Qassem Soleimani: Fallout in pictures People make their way on the street while a screen on the wall of a cinema shows a portrait Soleimani in Tehran AP US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Aziz Asmar, one of two Syrian painters who completed a mural following the killing of Iranian Revolutionary Guards commander Qasem Soleimani poses next to his creation in the rebel-held Syrian town of Dana in the northwestern province of Idlib AFP via Getty US airstrike kills Iran's Qassem Soleimani: Fallout in pictures A demonstration in Tehran AFP via Getty US airstrike kills Iran's Qassem Soleimani: Fallout in pictures An anti-US demonstration to condemn the killing of Soleimani, after Friday prayers in Tehran EPA US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Mujtaba al-Husseini, the representative of Iran's supreme leader Ayatollah Ali Khamenei, delivers a speech in the holy shrine city of Najaf AFP via Getty US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Pakistani Shiite Muslims burn a mock of a US and Israeli flags as they hold pictures of General Qasem Soleimani during a protest against the USA, outside the US Consulate in Lahore, Pakistan EPA US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Protesters demonstrate in Tehran AP US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Pakistani Shi'ite Muslims hold pictures of General Qasem Soleimani during a protest against the USA, in Peshawar, Pakistan EPA US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Protesters, holding a photograph of the leader of the People's Mujahedin of Iran Massoud Rajavi, outside Downing Street in London PA US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Protesters burn a US flag in Tehran AP US airstrike kills Iran's Qassem Soleimani: Fallout in pictures A Syrian man offers sweets to children to mark the killing AFP via Getty US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Iranian worshippers attend a mourning prayer for Soleimani in Iran's capital Tehran AFP via Getty US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Kashmiri Shiite Muslims shout anti American and anti Israel slogans during a protest AP US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Iranian worshipers chant slogans during Friday prayers Reuters US airstrike kills Iran's Qassem Soleimani: Fallout in pictures A protest against the USA, in Islamabad, Pakistan EPA US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Iranians burn a US flag in Tehran EPA US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Supporters of the National Council of Resistance of Iran in Germany (NWRI) protest outside Iran's embassy in Berlin, Germany Reuters US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Supporters of the National Council of Resistance of Iran in Germany (NWRI) protest outside Iran's embassy in Berlin Reuters US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Iranian worshippers in Tehran AFP via Getty US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Vehicles of the United Nations Interim Forces in Lebanon (UNIFIL) patrol a road in the southern Lebanese town of Kfar Kila near the border with Israel. Following morning's killing of Major General Qasem Soleimani, Lebanon's Iran-backed Hezbollah movement called for the missile strike by Israel's closest ally, to be avenged AFP via Getty US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Iranian women take to the streets in Tehran EPA

“A nation that willfully destroys another country's heritage would be no better than the criminals who have destroyed irreplaceable sites in Syria, Afghanistan, Iraq and elsewhere in recent years,” argued Sara C Bronin, a lawyer and specialist in historic preservation, in an op-ed for the Los Angeles Times in response to Mr Trump's threats to target cultural sites in Iran.

“Targeting civilians and cultural sites is what terrorists do. It's a war crime,” tweeted senator Chris Murphy, a member of the Senate Foreign Relations Committee.

In Britain, a spokesman for prime minister Boris Johnson cautioned that “there are international conventions in place which prevent the destruction of cultural heritage”.

Ironically, it was the US that for decades helped shape what some believed to be a new consensus on the destruction of cultural heritage: that this form of war and destruction is not only a crime against another warring party but a crime against humanity that endangers civilian lives and dignity.

In March 2017 – only weeks after Mr Trump's inauguration – the UN Security Council, with the US as a permanent member, unanimously adopted a resolution condemning the “unlawful destruction of cultural heritage, inter alia destruction of religious sites and artefacts” in armed conflicts.

Attacks on cultural heritage sites have been a frequent feature of armed conflicts throughout the history of civilisation. In 149 BC, for example, the Romans began their siege of Carthage, a North African city in what is now Tunisia. The assault ended in the total destruction of the city in what some researchers argue was an attempt by the Romans to eradicate their enemies' culture.

Carthage was once the heart of a powerful Mediterranean empire before being leveled by the Romans in 146 BC (AFP)

Much later, the 20th century's brutality reinforced calls for attacks on heritage sites to be more forcefully condemned. Second World War not only put a spotlight on the Nazis' attempts to attack opponents' dignity and national identity; it also raised questions over some Allied attacks. The Allied forces' bombardment of the eastern German city of Dresden – which came late in the war and surprised many who had not previously perceived the historic city to be a key military target – triggered a debate that continues to this day.

The international community appeared determined to take international treaties more seriously going forward.

According to the 1954 Hague Convention for the Protection of Cultural Property in the Event of Armed Conflict, warring parties should take all possible steps “to protect cultural property”, which includes “monuments of architecture, art or history, whether religious or secular”, among other examples.

UNESCO declared the ruins of Persepolis a World Heritage Site in 1979 (AFP)

(Under certain circumstances, the convention allows for cultural property's special protection to be withdrawn in case of “unavoidable military necessity”.)

Those commitments were also codified in the differently worded Geneva Conventions, which protect “historic monuments, works of art or places of worship which constitute the cultural or spiritual heritage of peoples” from acts of hostility.

In the 90s, the wars that broke up Yugoslavia became a brutal reminder of why such treaties had been drafted – and how they were ignored. Starting in 1991, Yugoslav People's Army forces besieged the historic city of Dubrovnik in Croatia, leading to the destruction of parts of its centre.

Dubrovnik was hit with heavy bombing which destroyed large parts of the historical city (AFP)

In the city of Sarajevo, in Bosnia, the Vijecnica city hall was set on fire in 1992, destroying its sizeable library.

In the aftermath, former prosecutors and researchers with the International Criminal Tribunal for the former Yugoslavia assessed more broadly that during conflicts, “it is increasingly evident that cultural property is not simply at risk from incidental harm, but is being intentionally attacked as part of cultural cleansing campaigns.”

They specifically referred to the conflicts in Syria and Iraq that were underway by the time of their assessment's publication in 2016. Militants in those countries – including Isis fighters – had launched a campaign against historic cultural artefacts and buildings that reverberated across the region.

As a result, the international community moved closer to ostracising such acts.

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In 2016, North African militant Ahmad al-Faqi al-Mahdi was convicted by the International Criminal Court (ICC) of “intentionally directing attacks against historic monuments and/or buildings dedicated to religion” in the ICC's first such trial, focusing on the destruction or damaging of cultural property. Mahdi was sentenced to nine years in prison for his role in attacking nine mausoleums and one mosque in Timbuktu, Mali, in 2012.

The ICC's message to the world at the time appeared to be: Attacks on cultural heritage will no longer go unpunished.

But with a US president now threatening to attack cultural targets in Iran, the narrative that the US helped to advance now appears in doubt.

“They're allowed to kill our people,” Mr Trump told reporters on Sunday, attempting to justify his threat. “They're allowed to torture and maim our people. They're allowed to use roadside bombs and blow up our people. And we're not allowed to touch their cultural site? It doesn't work that way.”