Trump called the agreement between Iran and the world’s six major powers the worst deal in his lifetime. Photograph by Olivier Douliery/Sipa USA via AP

Donald Trump was at his most bombastic this week in Washington. “We are led by stupid, stupid people—very, very stupid people,” he shouted at a rally on Wednesday held to protest the Iran nuclear deal. Three days earlier, he had embarrassed himself—if he is capable of embarrassment—by commenting on a recent SurveyUSA poll showing that he would beat Hillary Clinton in a head-to-head race. “Thank you!” he tweeted, with a link to an article about the poll. The story he cited was actually from Iran’s Press TV, the English-language and quasi-propagandistic news outlet of the Iranian regime.

At the rally, which was held on the steps of the Capitol, Trump called the agreement between Iran and the world’s six major powers the worst deal—of any kind, apparently—in his lifetime. “So I’ve been doing deals for a long time,” he told the crowd. “I’ve been making lots of wonderful deals, great deals. That’s what I do. Never, ever, ever in my life have I seen any transaction so incompetently negotiated as our deal with Iran. And I mean never.”

The shallowness (and callousness) of Trump's grasp of foreign policy became even clearer when he addressed the complex issue of American hostages detained in Iran, including a former F.B.I. agent who was last sighted there. “If I win the Presidency, I guarantee you that those four prisoners are back in our country before I ever take office,” he said at the rally. “They will be back before I ever take office, because they”—the Iranians—“know that’s what has to happen, O.K.? They know it. And if they don’t know it, I’m telling them right now.”

I’ve covered hostage dramas for a quarter century—the Americans seized at the U.S. Embassy in Tehran, in 1979; American colleagues seized by pro-Iranian groups when I lived in Beirut, in the nineteen-eighties; friends picked up while visiting relatives in Iran during the last eight years; the three American hikers picked up on the border with Iraq, in 2009. In every case, the hostages’ releases involved intricately orchestrated negotiations done through hundreds of channels and dozens of countries, and which often spanned years. After Trump’s speech, I asked some former hostages and U.S. officials involved in past and current hostage crises what they thought of Trump’s hostage policy.

“It doesn’t make sense,” Terry Anderson, America’s longest held hostage, told me. In 1985, Anderson was kidnapped in Beirut, where he was the Associated Press bureau chief, by Hezbollah, an Iranian proxy. “The Iranians aren’t at Trump’s beck-and-call, and they won’t be if he’s elected President,” Anderson said. “It’s so idiotic that I don’t know how to address it. One of the first things a President learns when he comes into office is that he can’t simply order things and make them happen—in our government, let alone anyone else’s.”

Anderson’s release involved a special U.N. envoy travelling the world, interventions by dozens of countries, and a war (not involving Iran) that altered the terms of the negotiations. The process took seven years, spanning two Presidencies. Anderson was finally freed in 1991. “Trump probably couldn’t tell you the difference between a Sunni and a Shiite,” Anderson said. “He’s a simple-minded twit.”

Others called Trump’s boast dangerously counterproductive. Haleh Esfandiari, who was the director of Middle East programs at the Woodrow Wilson International Center for Scholars, in Washington, was detained in Tehran while visiting her ailing ninety-three-year-old mother, in 2007. She was held for eight months, including for more than a hundred days in solitary confinement, at Tehran’s Evin Prison, which has become notorious for holding political prisoners following the revolution, in 1979. She called Trump’s claims “frivolous and irritating” and added, “This is of no help to the Iranian Americans in prison in Iran and is certainly not going to get them free."

John Limbert was one of the fifty-two Americans held for four hundred and forty-four days during the takeover of the U.S. Embassy in Tehran. He called Trump naïve. “The problem is that it’s always Iran’s decision on criteria [for freeing hostages], which we don’t know now and have never understood very well,” he said. “It’s easy for him to say these things, but it doesn’t help the detainees to make glib comments.”

Ronald Reagan, Limbert said, exploited the first hostage drama during the 1980 Presidential campaign but ended up implementing the terms agreed to by Jimmy Carter in order to win the hostages' freedom. Six years later, Reagan engaged in his own arms-for-hostage swap with Iran to win freedom for three Americans kidnapped in Beirut. It was Reagan’s most embarrassing move as President.

At the rally, Trump implied, without mentioning specifics, that he’d threaten whatever it took to win freedom for hostages and detainees. Sarah Shourd, who was one of the three American hikers detained in Iran, in 2009, told me this week, "The U.S. government threatening Iran has never resulted in any hostages being released, or any progress in negotiations on larger issues. U.S. bullying only strengthens the position of hard-liners in Iran's government: that the U.S.'s agenda is not to find common ground but to dominate."

The Michigan congressman Dan Kildee, a Democrat, has been deeply involved in the current case of Amir Hekmati, a former Marine who has spent four years in an Iranian prison. Born in Arizona, Hekmati served in Operation Iraqi Freedom. He went to Iran to visit his ailing grandmother in 2011. He was picked up just days before he was scheduled to fly home to start school at the University of Michigan. “It’s a thorny set of issues,” Kildee told me.

Hekmati was charged with espionage, waging war against God, and corrupting the earth. In 2012, he was sentenced to death. The sentence was overturned on appeal. According to the family, he was retried in secret—without being present or without any defense by his lawyer—and sentenced to ten years for “coöperating with foreign governments.”

“It’s particularly dangerous for Trump or any candidate to use the status of these Americans and the pain their families have been experiencing to advance his own political purposes,” Kildee said. “My effort to free Amir has been a bipartisan effort.”

This summer, Kildee won unanimous support in the House for a resolution on the Americans held in Iran. “It’s not the loudest voice or the most caustic language that gets things done, whether in domestic policy or international relations,” Kildee said. “It takes more than holding the microphone to actually make progress in this country. Name-calling should not have a place in American political space—especially in a subject as sensitive as Iran nuclear negotiations or the status of Americans held against their will.”

More troubling than Trump’s ignorance, perhaps, is his disdain toward learning the basics of foreign policy—not only when it comes to Iran, but regarding all national-security challenges. In an interview last week with the conservative radio host Hugh Hewitt, Trump failed to recognize the name of Qassem Soleimani, the infamous commander of Iran’s Quds Force, the élite arm of the Revolutionary Guards, which has plotted against American forces and the country's interests throughout the Middle East. Trump then confused the Quds Force with the Kurds, who are allied with the United States.

Hewitt pressed Trump on whether he even knew the players—including the leaders of Hezbollah, Al Qaeda, the Al Nusra Front, and the Islamic State—without a scorecard. “No, you know, I’ll tell you honestly,” Trump replied. “I think by the time we get to office, they’ll all be changed. They’ll all be gone.” Some of those leaders have been in power—and in the headlines—for decades.

Hewitt, who will be one of the team of panelists questioning candidates at the September 16th Republican debate hosted by CNN, pressed Trump on whether candidates should be able to address the world’s deadliest extremist movements and their differences.

Trump ridiculed the idea. “I’m a delegator,” he said. “I find absolutely great people. . . . But when you start throwing around names of people and where they live and give me their address, I think it’s ridiculous, and I think it’s totally worthless.”