text: The announcement of a prisoner exchange deal between the United States and Iran could increase the prospects for further diplomatic cooperation, including the Biden administration’s longstanding goal of containing Iran’s nuclear program, according to officials and analysts.
  While multiple flash points and deep-seated hostilities exist between Washington and Tehran, including Iranian threats to shipping traffic in the Persian Gulf and Iran’s support for Russia’s war in Ukraine, the success of a painstakingly negotiated prisoner agreement removes a severe problem from a relationship that is never far from military confrontation.
  Under the deal announced on Thursday, Iran will release five Iranian Americans from custody in return for the freeing of five Iranians jailed in the United States, along with the unfreezing of some $6 billion in Iranian assets for humanitarian purposes under strict monitoring.
  “The prisoner deal is a key step forward for Washington and Tehran’s efforts to lower tensions as they eye a return to formal nuclear negotiations later this year,” said Henry Rome, a senior fellow at the Washington Institute for Near East Policy.
  The deal comes as Iran and the United States appear to be observing an informal agreement under which Iran has limited its nuclear program and restrained proxy militias in Iraq and Syria to avoid harsh American reprisals.
  U.S. officials have repeatedly denied that they reached any nuclear “deal” with Iran after indirect talks held in Oman earlier this year. But officials from several countries have described those discussions, and Iran appears to be adhering to an agreement. Its parameters include Iranian enrichment of uranium at purity levels no higher than 60 percent, and no significant attacks on U.S. troops by Iranian proxy forces in Syria and Iraq.
  Two senior Israeli defense officials said the deal involving the prisoners and the frozen funds is part of the broader understandings reached in Oman. These understandings, according to the officials, are already being implemented on the ground. One senior U.S. military official said that there has been decreased activity by Iran-backed militias in Syria and Iraq against U.S. troops there in recent weeks. One of the Israeli officials added that while Iran has sent military assistance, including potent drones, to Russia since its invasion of Ukraine last year, Moscow would like more than it has received.
  Mr. Rome said the Biden administration likely hopes that formal nuclear talks organized by the European Union could restart later this year. The negotiations, aimed at restoring the 2015 Iran nuclear deal from which President Donald J. Trump withdrew in 2018, collapsed last summer amid what U.S. officials called unacceptable Iranian demands.
  But Mr. Rome added the Biden administration was unlikely to want a new nuclear agreement ahead of the 2024 election, given the issue’s political volatility. Iran may feel the same way, given Mr. Trump’s possible return to the Oval Office. A key reason talks to restore the nuclear deal failed last year was Tehran’s insistence on guarantees that a future president, perhaps Mr. Trump himself, would not renege again on the deal — which the Biden administration could not promise.
  The difference between an informal agreement on nuclear issues and a formal one is politically important. A formal deal would likely require approval from the U.S. Congress, where even many Democrats are skeptical of any steps to provide Iran’s repressive authoritarian government with economic and political relief. An informal understanding allows the Biden administration to sidestep Congress, much to the annoyance of many Republicans. Some of them complained on Thursday that the deal to release the Americans, who U.S. officials say were held on phony charges, had rewarded Iran with billions of dollars for de facto hostage taking.
  Defusing the slow-boiling crisis around Iran’s nuclear program, which has expanded in recent years to put Tehran within reach of nuclear weapons capability, is an urgent priority for the Biden administration. President Biden has no desire for a Middle East crisis — one that could be triggered by the United States or an Israeli attack on Iran’s nuclear facilities — as he seeks re-election.
  Iranian news media presented the deal as a victory for the conservative administration of President Ebrahim Raisi and called it “honorable diplomacy.” But Iranian analysts said that building on the good will of the prisoner exchange to reach broader agreements on Iran’s nuclear and military programs still remained challenging.
  Iran’s hard-liner faction is fiercely opposed to giving any more concessions to the United States beyond the existing framework of the 2015 nuclear deal. Supreme leader Ayatollah Ali Khamenei has said that Iran’s missile and drone programs are a matter of defense and nonnegotiable.
  Still, many Iranians celebrated the prisoner deal on Thursday, hopeful that it might be a step toward a loosening of sanctions imposed on Iran after Mr. Trump withdrew from the nuclear deal.
  “We pray that the deal today is part of a series of negotiations for a broader agreement that lifts all sanctions and brings relief to the Iranians,” Nasrollah Zarei, an Iranian oil and energy expert, said in a public discussion on the Clubhouse social networking app.
  The 2015 deal, which limited Iran’s nuclear program in return for sanctions relief, offered a spark of hope that the two countries might move past the specter of military confrontation that had long shadowed the relationship.
  But better relations didn’t come to pass. When Mr. Trump withdrew from the nuclear deal in 2018, he piled new sanctions onto Iran’s economy, choking off its oil exports. Iran accelerated its atomic program and has now stockpiled enough uranium enriched to near bomb-grade levels to make several nuclear bombs, although many analysts believe it could take Iran more than a year, possibly even two, to construct a workable nuclear device.
  Mr. Biden came into office hoping to negotiate a quick restoration of the nuclear deal, and U.S. and European officials spent more than a year negotiating with Tehran before the talks collapsed last summer.
  Relations have been tense since then, as U.S. officials have warned Iran that enriching uranium to a purity level of 90 percent risks the most severe consequences — effectively code for military action.
  The United States believes that Iran has sponsored recurring attacks on U.S. troops in the Middle East by Tehran’s proxy forces. Iran has also tried to seized commercial ships in the Strait of Hormuz and the Gulf of Oman in recent weeks.
  That prompted the deployment this month of thousands of U.S. sailors and Marines “to support deterrence efforts” in the region, according to a Defense Department announcement on Aug. 7.
  At the same time, Iran has moved to de-escalate relations with Saudi Arabia, another of its main rivals, through a deal in March to restore diplomatic ties after a seven-year freeze. That could suggest that Iran’s government desires a less confrontational foreign policy.
  But some analysts cautioned against raising expectations for future diplomacy, saying that the prisoner deal was probably not a sign of any larger diplomatic opening.
  “The Islamic Republic’s enmity toward the United States is central to its identity as a revolutionary power,” said Karim Sadjadpour, an analyst at the Carnegie Endowment for International Peace. “It needs America as an adversary for its own internal legitimacy. It is willing to cut tactical deals on hostages and nukes when it behooves them economically, but its hostility toward the U.S. is strategic and enduring.”
  Richard Goldberg, a former National Security Council official in the Trump White House who is now with the hawkish Foundation for the Defense of Democracies, denounced the agreement to free prisoners as an incentive for other countries to unjustly imprison Americans and then seek what amounts to ransom for their release.
  He also expressed concern that the Biden administration was striking de facto security agreements with Iran in secret.
  “It’s a double whammy — a horrible hostage policy precedent with broad ramifications for Americans abroad and a continuation of a nuclear deal negotiated in secret absent congressional review,” he said.
  Perhaps mindful of such criticisms, Secretary of State Antony J. Blinken was careful on Thursday to insist that the United States maintains a tough stance.
  “We will continue to enforce all of our sanctions, we will continue to push back resolutely against Iran’s destabilizing activities in the region and beyond,” Mr. Blinken told reporters.
  “None of these efforts take away from that. These are entirely separate tracks,” he said. “We are focused on getting our people home, but we continue to take strong action against Iran’s other activities that we and so many other countries profoundly object to.”
  Eric Schmitt contributed reporting from Washington.