Power plants, desalination stations, oil wells, roads, bridges and other infrastructure.

They are the foundations of civilian life in Iran, and their destruction by American and Israeli forces would cause widespread suffering among the country’s 93 million people — and in most cases would be considered a war crime under international law.....

The president was emphatic about the targets in a follow-up post: “Tuesday will be Power Plant Day, and Bridge Day, all wrapped up in one, in Iran. There will be nothing like it!!! Open the Fuckin’ Strait, you crazy bastards, or you’ll be living in Hell — JUST WATCH. Praise be to Allah.”,.....

No other recent American president has talked so openly about committing potential war crimes, legal experts, historians and former U.S. officials say. Wartime American presidents and their aides have usually insisted they were trying to follow international and U.S. military law, even if they violated it in some cases.

International laws aimed at preventing the horrors of total war are codified in a series of agreements, including the Geneva Conventions, the Hague Conventions, the Nuremberg Principles and the United Nations Charter. Deliberate attacks on civilians and civilian infrastructure violate those. So does pillaging a country, which Mr. Trump has suggested he might do by taking Iran’s oil.....

The American president has been unambiguous in his disdain for international law. In a two-hour Oval Office interview in January with The New York Times, Mr. Trump declared, “I don’t need international law.” When asked whether there was any limit on his global powers, he said, “Yeah, there is one thing. My own morality.”....

The administration’s language has alarmed many legal experts, who say the signal being sent to U.S. service members — and to foreign nations, including adversaries — shapes behavior on the battlefield.

One hundred legal experts and lawyers voiced their concerns in an open letter published by Just Security last week. They said that the conduct of the war and rhetoric of U.S. officials “raise serious concerns about violations of international humanitarian law, including potential war crimes.”

They pointed out that the very act of the United States’ attacking Iran is a violation of the U.N. Charter, since there is no evidence Mr. Trump was acting to defend his country against an imminent threat. And the president did not get congressional authorization for the war, in violation of the Constitution......

During a standoff with Iran in his first administration, Mr. Trump threatened to destroy 52 cultural sites in the country. Mark T. Esper, then the defense secretary, acknowledged that hitting such sites would be a war crime and said the Pentagon would not do it.

The second Trump administration has taken a different approach.