WHITE HOUSE - Threats by U.S. President Donald Trump to destroy Iranian cultural sites are generating widespread international condemnation and accusations it would be a war crime.

It is also seen as a reversal of an American code of conduct dating back to the Civil War administration of Abraham Lincoln.

"The history of the American military of protecting cultural sites when possible, goes back over 150 years. The military and the United States, more broadly, is rightly proud of that," according to Depaul University Law Professor Patty Gerstenblith, director of the school's Center for Art, Museum and Cultural Heritage Law.

"Both at the U.S. national level and internationally, the thought of using an attack on cultural heritage as a form of retaliation and reprisal — which is what this would be — is really abhorrent," Gerstenblith, a former chair of the President's Cultural Property Advisory Committee in the Obama administration, told VOA.

Some of the criticism of Trump's threats is coming from among America's closest allies.

"We've been very clear that cultural sites are protected under international law and we would expect that to be respected," said British Foreign Minister Dominic Raab.

Mourners attend a funeral ceremony for Iranian Gen. Qassem Soleimani and his comrades, who were killed in Iraq in a U.S. drone strike on Friday, at the Enqelab-e-Eslami (Islamic Revolution) square in Tehran, Iran, Jan. 6, 2020.

Speaking to reporters Sunday evening on Air Force One, Trump doubled down on an earlier tweeted threat to attack sites of cultural importance if Tehran retaliates for last week's lethal strike by a U.S. military drone on Iranian General Qassem Soleimani, who was blamed for numerous terrorist attacks internationally.

"They're allowed to kill our people," said the president during the flight to Joint Base Andrews in Maryland from Florida. "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 sites? It doesn't work that way."

Asked on Monday by a reporter at the Pentagon whether the United States would strike cultural sites in Iran, Defense Secretary Mark Esper replied, "We will follow the laws of armed conflict."

Opposition to threat

A former director of national intelligence, James Clapper, said he believes such attacks by the United States would violate international law.

"We would incur the wrath of the international community if we did so and potentially put such targets in the United States at risk from attack by sleeper cells," Clapper told VOA. "I'm sure his list of targets is news to the Pentagon, whom I'm sure has done no serious planning for such targets."

FILE - Then-Director of National Security James Clapper testifies before the House Intelligence Committee on Capitol Hill in Washington, Feb. 2, 2012.

Before becoming DNI under former President Barack Obama, Clapper served as under-secretary of defense for intelligence in two different administrations.

Clapper said attacking cultural targets "would only serve to heighten the emotions of the Iranians, and, ironically, galvanize them to support the regime — the exact antithesis of what we've allegedly been pursuing with our 'maximum pressure' campaign, which has shown itself to be an abject failure."

A former senior director of the White House situation room agreed.

"This can only increase the threat to Americans. When the U.S. President makes it open season on cultural sites, he offers false justification to adversaries to do the same," Larry Pfeiffer, also a former chief of staff to the director of the Central Intelligence Agency, told VOA.

"These threats sound like something that would be issued by an autocratic regime like North Korea," added Pfeiffer, director of the Hayden Center for Intelligence, Policy and International Security at George Mason University. "This is not how America should behave and likely would violate international conventions and norms. This is what the Taliban did to universal condemnation. And this targeting makes it difficult for our western allies to support U.S. goals."

The Taliban, while in power in Afghanistan in 2001, dynamited giant Buddha statues that dated back to the 6th century.

"Secretary [of State Mike] Pompeo said yesterday that we will be within the law, and I think that Iran has many military, strategic military sites, that you may cite are also cultural sites," Kellyanne Conway, counselor to the president, told White House reporters on Monday.

Asked if she was accusing the Iranians of camouflaging military equipment within cultural sites, Conway replied: "No, I wouldn't say that," before adding, "I mean, maybe. Who knows?"

'War crime'

The Hague Convention recognizes situations where an attack on cultural property may be lawful, such as when the site has been turned into a military objective and an attack would be required by "imperative military necessity," according to international law experts.

The law, however, prohibits the destruction of cultural property as a means of intimidating people under occupation or as a reprisal, as is implied by Trump's statements, according to scholars.

Iran foreign minister, Javad Zarif, tweeted on Sunday "targeting cultural sites is a WAR CRIME."

-Having committed grave breaches of int'l law in Friday's cowardly assassinations, @realdonaldtrump threatens to commit again new breaches of JUS COGENS;



-Targeting cultural sites is a WAR CRIME;



-Whether kicking or screaming, end of US malign presence in West Asia has begun. — Javad Zarif (@JZarif) January 5, 2020

During a Monday meeting between the director-general of the United Nations Educational, Scientific and Cultural Organization, Audrey Azoulay, and Iranian Ambassador Ahmad Jalali, the U.N. agency head noted both the United States and Iran had ratified two legal instruments protecting world cultural sites in armed conflict.

Azoulay also pointed out that U.N. members in 2017 unanimously approved a resolution condemning acts of destruction of cultural heritage.

Trump's administration withdrew the United States from UNESCO in 2018.

An al-Qaida-linked extremist was convicted of war crimes in 2016 by the International Criminal Court for destroying historic and religious artifacts in Mali.

The United States, however, does not recognize the jurisdiction of the court based in The Hague.

WATCH: Analysts predict no war with Iran

WWII targets

In the closing days of the Second World War, the U.S. military placed Japan's former capital of Kyoto at the top of its list to be the target for the first atomic bombing.

Secretary of War Henry Stimson persuaded President Harry Truman to spare the city dotted with thousands of sites of religious and cultural importance.

Stimson, in his diary, recalled telling Truman in July of 1945 he "did not want to have the United States get the reputation of outdoing [Nazi party leader Adolf] Hitler in atrocities."

The Allies, months earlier, conducted a heavy bombardment of Dresden, a German cultural landmark. Military officers defended the raids, noting the city's major rail hub, communications centers and 100-plus factories in support of the Axis war effort.

A special U.S. Army unit during the war in Europe sought to redirect Allied bombing raids away from German cathedrals and recovered thousands of valuable items of art looted by the Nazis.

Their mission was dramatized in a 2014 movie "The Monuments Men," starring George Clooney.

Gerstenblith, author of "Art, Cultural Heritage, and the Law," said she hopes Trump will take inspiration from the tradition of "The Monuments Men" and that his threats to destroy artifacts of history will turn out to be "just bluster."

Jeff Seldin, Patsy Widakuswara and Carla Babb contributed to this report.