Candidate Donald Trump campaigned against Washington’s foolish Middle East wars. President Donald Trump is threatening Tehran with the equivalent of fire and fury. After decades of American attacks on Iran, what Trump should be doing is changing course.

The president erupted against Iran on Twitter earlier this week in an outburst that was even more hysterical than his tirade against North Korea last year. “NEVER, EVER THREATEN THE UNITED STATES AGAIN OR YOU WILL SUFFER CONSEQUENCES THE LIKES OF WHICH FEW THROUGHOUT HISTORY HAVE EVER SUFFERED BEFORE,” he tweeted. “WE ARE NO LONGER A COUNTRY THAT WILL STAND FOR YOUR DEMENTED WORDS OF VIOLENCE & DEATH. BE CAUTIOUS!”

The president sounded like a high school dropout who had just downed a six-pack and was now itching for a brawl. It’s he who should be cautious before enthusiastically threatening to visit death upon another nation and people. After all, as he once acknowledged, the results of U.S. warmongering have been ugly.

America has been in conflict with Iran, or more accurately the Iranian people, for decades. In 1953, Washington backed a coup that overturned a democratically elected government. Five presidents supported Mohammad Reza Pahlavi, Iran’s shah, who governed as an absolute monarch. His rule was highlighted by ostentatious corruption, brutal repression, nuclear research, and plans to become the Middle East’s dominant power.

A broad coalition overthrew the shah in 1979, but alas the worst guys with the most guns, the Islamists, gained control. The U.S. then backed Iraq’s aggressive war against Iran, started by Saddam Hussein (yes, that Saddam Hussein). The Reagan administration provided Baghdad with intelligence and dual-use technology that Saddam used to create chemical weapons. Washington also reflagged Kuwaiti oil tankers as American vessels to protect the small Gulf state, which was helping to fund Iraq’s war.

In 1988, while that conflict raged, a U.S. ship shot down an Iranian commercial airliner, killing 290 people. The Pentagon initially misstated the facts to shift blame. Two years later, the U.S. Navy awarded the captain who had given the orders to fire the Legion of Merit for “outstanding service.”

In 2003, the Bush administration rejected Iran’s offer to talk about all issues. As the neoconservative Greek Chorus urged Washington on to Tehran, the administration’s John Bolton reportedly said that such an attack was forthcoming. Even the Obama administration threatened Tehran with war, routinely intoning that “all options are on the table.” That threat was issued not to deter an Iranian attack, but to dissuade Tehran from building a deterrent to an American attack. In 2015, then-commentator and now-national security advisor Bolton erroneously proclaimed that Iran would not negotiate away its nuclear weapons and advocated for war.

Trump launched a multifaceted assault on Tehran: banning Iranians from entering the U.S., even Christians previously cleared as refugees; tearing up the multilateral nuclear accord that even his own secretary of defense supported; reinstating economic sanctions; issuing a steady stream of military threats; appointing war advocate Bolton as national security advisor; and subordinating America’s Middle East policy to the demands of Iran’s mortal enemy, Saudi Arabia, which has done far more to promote terrorism, spread war and instability, enforce autocracy, and suppress religious freedom than Iran. Riyadh’s barbaric aggression against Yemen alone is worse than any of Tehran’s international misadventures.

Is it any wonder that Iran fears the U.S. and wants a deterrent?

Indeed, Saudi Arabia treats the president as a hired hand. When former Pentagon chief Robert Gates met King Abdullah, he revealed that the monarch “wanted a full-scale attack on Iranian military targets, not just the nuclear sites,” which meant he “was asking the United States to send its sons and daughters into a war with Iran in order to protect the Saudi position in the Gulf and the region, as if we were mercenaries.” Which is precisely how the monarchy views us.

Of course, in his Sunday speech at the Ronald Reagan Presidential Library, Secretary of State Mike Pompeo professed concern for the Iranian people—who would be most at risk if the U.S. attacked, will suffer the most under renewed economic sanctions, and are barred from taking refuge in America. For this reason Jason Rezaian, the Washington Post Tehran bureau chief once jailed by Iran, observed with brutal understatement: “it is difficult for the administration to support its own claims that the well-being and prosperity of Iranians matter.”

The secretary attacked Iran as a kleptocracy: “The level of corruption and wealth among regime leaders shows that Iran is run by something that resembles the mafia more than a government.” But which leader considers the people’s entire wealth, including vast oil deposits, to be family property? Which leader squandered nearly a billion dollars on a yacht and French chateau? Which leader spends lavishly to buy American policy? Surely the Saudis fit that description far more than do the Iranians.

Pompeo should read what his own department says about the Saudi royals. The most significant abuses, State’s human rights report notes, “included unlawful killings, including execution for other than the most serious offenses and without requisite due process; torture; arbitrary arrest and detention, including of lawyers, human rights activists, and antigovernment reformists; political prisoners; arbitrary interference with privacy’ restrictions on freedom of expression, including on the internet, and criminalization of libel; restrictions on freedoms of peaceful assembly, association, movement, and religion; citizens’ lack of ability and legal means to choose their government through free and fair elections.”

State also put out a separate analysis on religious liberty, short but sour: “Freedom of religion is not provided under the law. The government does not allow the public practice of any non-Muslim religion.” Shiite Muslims also suffer. The Saudi “government convicted and imprisoned individuals on charges of apostasy, blasphemy, violating Islamic values and moral standards, insulting Islam, black magic, and sorcery.”

And Pompeo cried crocodile tears over Iran’s human rights violations?

The administration’s apparent solution is regime change. Of course, a democratic alternative to the repressive Islamist regime in Tehran would be wonderful, but the most likely replacement would be a more radical and repressive government. Violent chaos rarely results in liberty.

Apparently some Trump officials, such as Bolton, believe the Mujahedin-e Khalq, or MEK, could take over. Created a half century ago, MEK mixed Marxism and Islamism, violently resisted the U.S.-backed Shah, attacked American firms and killed U.S. contractors and soldiers, and backed Saddam Hussein (yes, that Saddam Hussein) against their own country. The cultish group lost most of its popular support when it waged war on its own people. They got off the U.S. terrorism list only through high-powered lobbying. It’s unlikely they’ll ever come to power in Iran except atop U.S. tanks.

Such a war would be no cakewalk. Of course, Washington would win any conventional conflict, but the aftermath would likely be far bloodier than Iraq. Iran has a bigger economy, a larger and more sophisticated population, and better organized support for its regime. It is a real country, with a civilization (Persia) that stretches back thousands of years. Even those friendly to America are unlikely to welcome war on themselves.

A war on Iran would probably disrupt the global oil trade, if nothing else creating uncertainty and raising petroleum prices and insurance rates. Moreover, Tehran might also open additional fronts—against Israel and the potentially fragile Gulf kingdoms, for example. Many if not most Shiite Iraqis would likely favor their co-religionists over their onetime occupiers.

Instead of threatening war on behalf of the Saudi royals and demanding Iran’s de facto surrender, the president should build on the nuclear agreement, which halted Iranian movement toward atomic weapons. Increasing Iranian contact with the rest of the world would also sharpen that nation’s internal political conflict by highlighting the opportunities available through peaceful engagement.

The Obama administration had the right strategy but it underestimated the challenge: powerful authoritarians never yield easily. However, transformation is more likely to come when Washington stops giving the Islamist regime excuses for repression. Peace and stability in the region is more likely if the U.S. reduces its military threats and frees itself from Riyadh’s grip.

Indeed, virtually every American intervention in the region has created violent, even disastrous blowback: entering Lebanon’s civil war, supporting even extremist Israeli governments, selling U.S. foreign policy to Saudi Arabia’s royals, invading Iraq, blowing up Libya, fueling the Syrian civil war, backing autocracy in Bahrain and Egypt, aiding Riyadh’s aggression against Yemen.

The administration’s greatest mistake today may be anointing Saudi Arabia as prospective regional hegemon, which would allow the Saudi crown prince to advance his reckless ambitions with little regard for Washington’s interests—like how Iran’s shah promoted his foolhardy imperial ambitions while backed by the U.S.

Iran is a dramatic example of the costs of arrogant, reckless American intervention. Washington and the Iranian people continue to pay a high price for past U.S. follies. It’s time for Trump to finally step back from the mess that his predecessors created.

Doug Bandow is a senior fellow at the Cato Institute. A former special assistant to President Ronald Reagan, he is author of Foreign Follies: America’s New Global Empire.