Iranian leaders fear being burned again by President Trump, who tore up a nuclear agreement reached during the Obama administration after lengthy negotiations.

President Trump and Iran’s leaders have wide differences on many issues, from nuclear technology to the Strait of Hormuz. But their main obstacle to striking a lasting peace agreement may be a matter of trust.

Always wary of the United States, Iranian officials consider Mr. Trump particularly treacherous. They remember the way, during his first term as president, Mr. Trump simply abandoned a nuclear deal Iran had struck with the Obama administration and other world powers after nearly two years of negotiations. Mr. Trump did not claim that Iran was violating that deal; he simply didn’t like it.

When the Biden administration tried to coax Iran into a similar agreement a few years later, Iran’s leadership demanded a guarantee that a future Trump administration would not simply tear it up again, according to former U.S. officials. They had no way of providing one.

And twice over the past year, Mr. Trump has entered into diplomatic talks with Iran only to launch airstrikes while negotiations were still in their early stages. In late February, Mr. Trump sent envoys to meet with Iranian officials in Geneva just one day before Iran’s supreme leader was killed in an airstrike that began weeks of U.S. and Israeli bombing. By the time of that meeting, Mr. Trump had already committed to war, according to U.S. officials.

After a first round of talks earlier this month ended in rancor, Iranian officials said a main reason was a U.S. failure to gain their trust. On Tuesday, Vice President JD Vance delayed his departure to Pakistan for a potential second round of talks, as Iranian officials again raised the point.

On Monday, Iranian state media reported that the country’s president, Masoud Pezeshkian, had warned in a Sunday phone call with Pakistan’s prime minister that “the U.S. seeks to repeat previous patterns and betray diplomacy,” according to the Islamic Republic News Agency.

Fearful of being burned again, Iran is insisting on incremental steps and retaining leverage — such as at least partial control of its uranium stockpile for as long as possible. But experts said Iran faced a disadvantage because any plausible deal would require it to take steps that would ultimately be irreversible, such as eventually surrendering its uranium supply.

The distrust is a busy two-way street: The United States says that Iran has routinely lied for years by claiming its nuclear program was for peaceful purposes only, and points to uncovered evidence of Tehran’s past military nuclear research. Iran has also flouted its international commitments by building secret underground nuclear facilities.

Mr. Trump has called Iran’s leaders “crazy,” “insane” and “lunatics.”

“Iran has spent decades deceiving the world about its nuclear program, hiding facilities, concealing materials and activities, and feeding the International Atomic Energy Agency false or incomplete information,” said Michael Doran, a former senior national security official in the George W. Bush administration. “That record leaves no basis for confidence in Iran’s assurances about its intentions.”

During nuclear arms talks with the Soviet Union, President Ronald Reagan popularized the phrase “trust, but verify.” It is unclear whether Iran and the Trump administration can even meet that standard.

“The level of trust between the United States and Iran has always been very low, but now it is nonexistent,” said Karim Sadjadpour, a senior fellow at the Carnegie Endowment for International Peace.

“The Islamic Republic believes the United States could attack at any moment, including during negotiations, as Trump has done twice before,” he added. “Washington will never believe the Islamic Republic has renounced its nuclear weapons ambitions, even if it agrees to a compromise.”

Iran has an added reason for skepticism in Mr. Trump’s military partnership with Prime Minister Benjamin Netanyahu of Israel. Mr. Netanyahu would like to resume the joint U.S.-Israeli bombing campaign as soon as an April 7 cease-fire agreement expires on Wednesday in Iran. Iranian propaganda has depicted Mr. Trump as Mr. Netanyahu’s “puppet,” and Iranian officials surely fear that the Israeli prime minister, who made a strong original case for war at the White House, will persuade Mr. Trump to abandon diplomacy.

Despite it all, both Mr. Trump and Iran appear willing to give diplomacy a try. They would hardly be the first enemies to overcome deceit and betrayal and reach a successful agreement. During his first term, Mr. Trump himself struck a deal with the Afghan Taliban — Islamist radicals who had fought the United States for 20 years — to withdraw American troops from the country.

Even if the two sides can overcome their expectations of treachery, the distrust complicates negotiations that Mr. Trump says can be concluded quickly. That is a blithe hope, according to veteran diplomats and Iran experts.

Designing a deal will require calibrating its step-by-step implementation to minimize the opportunities for one side to obtain an advantage and walk away.

“That too is complicated because most of the concessions required of Iran are concrete and irreversible, such as turning over or downblending its highly enriched uranium,” said Robert Malley, a lead negotiator with Iran during the Obama and Biden administrations.

“In contrast, most of the expected U.S. concessions are notional and reversible, such as lifting sanctions or providing access to frozen assets,” he added.

As a result, Mr. Malley said, Iran will insist “on a slow, incremental, step-by-step approach” to implementing any agreement, as a way to test Mr. Trump’s compliance.

But Mr. Trump, hardly known for his patience, may balk at that approach.

Looming over it all will be Iran’s memory of Mr. Trump’s abrogation of the Obama nuclear deal, known as the Joint Comprehensive Plan of Action, under which Iran agreed to 15 years of limits on its nuclear program in return for sanctions relief.

The agreement took some 20 months to negotiate, with Russia, China, Britain, Germany, France and the European Union joining the United States and Iran in countless rounds of talks. All agreed that Iran was in compliance with the agreement — until Mr. Trump arrived at the White House.

Calling the deal “a disaster,” Mr. Trump withdrew from it in 2018 and hammered Iran with new sanctions. In response, Tehran blew through the caps it had agreed to place on its nuclear program, enriching enough uranium to near-military grade levels to come within weeks of bomb-making capability. (Experts say it could still take Iran many months to build a nuclear bomb once it has refined enough uranium for the task.)

Mr. Trump cited that nuclear progress as grounds for striking its nuclear facilities last June. The strikes, known as Operation Midnight Hammer, came as the U.S. and Iran were negotiating through Omani mediators.

When Mr. Malley led indirect U.S. talks with Iran during the Biden administration, seeking to revive the Obama nuclear agreement, Iranian officials insisted on guarantees that the United States could not once again unilaterally withdraw from the deal. Mr. Malley insisted just as firmly that such a guarantee was not possible.

“Given the depth of mistrust, as well as the sensitivity of the issues being negotiated, it’s very unlikely a deal of this magnitude can be negotiated over a few weeks,” Mr. Sadjadpour said. “More commonly it has taken many months, if not years.”