WASHINGTON (NYTIMES) - US Defence Secretary Mark Esper sought to douse an international outcry on Monday (Jan 6) by ruling out military attacks on cultural sites in Iran if the conflict with Teheran escalates further, despite President Donald Trump's threat to destroy some of the country's treasured icons.

Esper acknowledged that striking cultural sites with no military value would be a war crime, putting him at odds with the president, who insisted such places would be legitimate targets. Trump's threats generated condemnation at home and abroad while deeply discomfiting US military leaders who have made a career of upholding the laws of war.

"We will follow the laws of armed conflict," Esper said at a news briefing at the Pentagon when asked if cultural sites would be targeted as the president had suggested over the weekend. When a reporter asked if that meant "no" because the laws of war prohibit targeting cultural sites, Esper agreed. "That's the laws of armed conflict."

The furore was a classic controversy of Trump's creation, the apparent result of an impulsive threat and his refusal to back down in the face of criticism. When Trump declared on Saturday that the United States had identified 52 potential targets in Iran if it retaliates for the American drone strike that killed General Qassem Soleimani, none of those targets qualified as cultural sites, according to an administration official who asked not to be identified correcting the president.

Nonetheless, when Trump casually said on Twitter that they included sites "very high level & important to Iran & the Iranian culture," the resulting uproar only got his back up.

Rather than simply say that cultural sites were not actually being targeted, the official said, he decided to double down the next day with reporters flying with him on Air Force One, scoffing at the idea that Iran could "kill our people" while "we're not allowed to touch their cultural site," saying, "It doesn't work that way."

The comments drew protests from Iran and other American adversaries who said they showed that Trump is the aggressor - and not just against Iran's government but against its people, its history and its very nationhood. Even some of America's allies weighed in, with Prime Minister Boris Johnson of Britain breaking with Trump by issuing a statement through an aide warning against targeting antiquities.

Military leaders were left in the awkward position of trying to reaffirm their commitment to generations of war-fighting rules without angering a volatile commander in chief by contradicting him. Trump's remarks unsettled even some of his allies, who considered them an unnecessary distraction at a time when the president should be focusing attention on Iran's misdeeds rather than promising some of his own.

"We're not at war with the culture of the Iranian people," Republican Senator Lindsey Graham of South Carolina, one of the president's staunchest supporters in Congress, said Monday. "We're in a conflict with the theology, the ayatollah and his way of doing business."

Graham, a retired military lawyer in the Air Force Reserve, said he delivered that message to Trump in a telephone call on Monday. "I think the president saying 'we will hit you hard' is the right message," he said. "Cultural sites is not hitting them hard; it's creating more problems. We're trying to show solidarity with the Iranian people."

Democratic Senator Jack Reed of Rhode Island, a member of the Senate Armed Services Committee, said Trump's threats would only encourage despots of the world to target antiquities themselves.

"America is better than that, and President Trump is flat-out wrong to threaten attacks on historic places of cultural heritage," said Reed, a former platoon leader in the Army's 82nd Airborne Division. "Destroying some of these culturally significant Iranian sites wouldn't be seen as just an attack against the regime in Tehran, it could be construed as an attack on history and humanity."

Iran, home to one of humanity's most storied ancient civilisations, has 22 cultural sites designated on the World Heritage List by Unesco, the United Nations cultural organisation, including the ruins of Persepolis, the capital of the Achaemenid Empire later conquered by Alexander the Great. Others include Tchogha Zanbil, the remnants of the holy city of the Kingdom of Elam, and a series of Persian gardens that have their roots in the times of Cyrus the Great.

The United States is a signatory to a 1954 international agreement to protect cultural property in armed conflict and has been a leader in condemning rogue nations and groups that destroy antiquities, including the Islamic State in Iraq and Syria's (ISIS) destruction of sites in Mosul, Iraq, and Palmyra, Syria, and the Taleban's demolition of the famed Bamiyan Buddhas in Afghanistan in 2001.

Experts said that what Trump described would likewise violate international law. "We and others accused ISIS of war crimes when they did this," said Jeh Johnson, a former homeland security secretary under President Barack Obama. "Certainly, in aggravated circumstances, it should be considered a war crime."

Johnson, who previously served as the top lawyer at the Pentagon, and others said there could be situations that are murkier, if the actual cultural value was less clear or it was being used as a military facility. Still, Johnson said, "my guess is his national security lawyers did not vet that tweet."