President Trump’s decision to abrogate the articles of appeasement with Iran is his finest hour — so far. Its message is woe to him who takes the American people for granted. That was the fundamental mistake made by President Obama and Secretary of State Kerry. They proceeded with a deal they knew the Congress of the United States opposed. They took it to the United Nations Security Council and voted there against our Congress and for the Iranians.

It is hard to imagine what they were thinking. The leaders of France, Britain, and Germany should have seen this a mile away. Yet they, too, went along, as did the Iranian camarilla. It is hard enough to imagine what any of them were thinking before the American voters went to the polls. It’s just impossible to see the logic of persisting in support of appeasement after the election, in which the American people were given such a clear choice.

The election in 2016 pitted two major candidates and required all 50 states to choose between them. One candidate, Secretary Clinton, had helped plot the Iran deal and, after she left office, had supported the work on it of Messrs. Obama and Kerry. She chose as her running mate a senator who led the boycott of the Joint Meeting of Congress at which Israel’s premier, Benjamin Netanyahu, stated the case against the pact. The Democrats went all in on appeasement.

What a contrast to Mr. Trump and the Republicans. Mr. Trump made it clear that should he win the presidency he intended to “tear up” the appeasement agreement. He stood on a Republican platform that put it this way: “We consider the Administration’s deal with Iran, to lift international sanctions and make hundreds of billions of dollars available to the Mullahs, a personal agreement between the President and his negotiating partners and non-binding on the next president.”

“Without a two-thirds endorsement by the Senate,” the GOP platform continued in respect of the pact, “it does not have treaty status. Because of it, the defiant and emboldened regime in Tehran continues to sponsor terrorism across the region, develop a nuclear weapon, test-fire ballistic missiles inscribed with ‘Death to Israel,’ and abuse the basic human rights of its citizens. A Republican president will not be bound by it.” The states decided, and the promise was redeemed.

“America will not be held hostage to nuclear blackmail,” Mr. Trump said. “We will not allow American cities to be threatened with destruction. And we will not allow a regime that chants ‘Death to America’ to gain access to the most deadly weapons on Earth.” Yet he also sent a wider message, disclosing that even as he spoke Secretary of State Pompeo was enroute by air to North Korea, to prepare for Mr. Trump’s meeting with Kim Jong-un.

“Plans are being made, relationships are building,” Mr. Trump averred. He expressed the hope that with North Korea “a deal will happen,” though by our lights it’s hard to imagine that such a deal could prosper without the North Koreans ending their shipments of military materiel to the Middle East. Mr. Trump held open the possibility of finding a “lasting solution to the Iranian nuclear threat,” including elimination of its missile program. He expressed eloquently America’s solidarity with the Iranian people who suffer under the current regime. Meantime, powerful sanctions will resume. The American people have spoken.