The U.S. and Iran are trading stunningly specific threats, with President Trump tweeting Saturday night that the military could target 52 Iranian sites — including some "important" to Iranian culture — and an Iranian commander pointing to "35 U.S. targets in the region as well as Tel Aviv."

Why it matters: This rhetoric suggests the off-ramp from a hot conflict may be fading, with Trump's warning about cultural sites prompting Iranian officials to accuse the president of flouting international law and threatening war crimes.

"Through MILLENNIA of history, barbarians have come and ravaged our cities, razed our monuments and burnt our libraries," Iranian Foreign Minister Mohammad Javad Zarif tweeted Sunday. "Where are they now? We're still here, & standing tall."

A 1954 Hague treaty makes targeting cultural sites a war crime, per AP. The UN Security Council also unanimously passed a resolution in 2017 condemning the destruction of heritage sites in response to attacks by the Islamic State.

Secretary of State Mike Pompeo downplayed Trump's tweets on the Sunday shows, declining to disavow the threat but assuring that the U.S. would behave inside international laws.

Iran's plans: Hossein Dehghan, the military adviser to Iran's supreme leader, told CNN in Tehran today that his country's response to the airstrike "for sure will be military and against military sites."

Dehghan called Trump's tweets "ridiculous and absurd," saying the president "doesn't know international law. He doesn't recognize UN resolutions either. Basically he is a veritable gangster and a gambler."

Trump's tweets "ridiculous and absurd," saying the president "doesn't know international law. He doesn't recognize UN resolutions either. Basically he is a veritable gangster and a gambler." Referring to the UN resolution condemning unlawful destruction of cultural heritage, Dehghan said that if Trump proceeded with his threat, "he should accept that he is a war criminal and must be tried in a relevant court."

The bottom line, per WashPost columnist David Ignatius: "It's as though the Middle East has played a cruel joke on Trump. The president who wanted so badly to escape the region that he abandoned a low-cost, high-success mission in northeast Syria is now stumbling into a hugely expensive adventure against Iran."

Go deeper: Iraqi parliament calls on government to expel U.S. troops