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President Barack Obama leaves the podium after speaking about the release of Americans by Iran, Sunday, Jan. 17, 2016, in the Cabinet Room of the White House in Washington.

President Obama on Sunday hailed the release of Americans from Iranian custody and the implementation of an historic accord to curb Iran’s nuclear program, pointing to the breakthroughs as products of diplomacy.

“The United States has never been afraid to pursue diplomacy. We could advance by engaging directly with the Iranian government,” Obama said in a statement from the White House. “We’ve seen the results.”

The organization tasked with inspecting and monitoring Iran’s nuclear stockpiles and sites formally certified Saturday that Tehran had fulfilled the commitments of the nuclear deal brokered last year and dismantled most of its nuclear program. Inspectors of the International Atomic Energy Agency said the country had taken concrete steps to scale back its nuclear infrastructure over the past three months—quite literally, as my colleague Matt Ford pointed out, as in the case of the nuclear reactor core at Arak, which was covered in concrete.

Administration officials say that if the Iranian government were to go back on the deal now, it would take more than a year for the country to create a nuclear bomb.

In exchange, President Obama signed an executive order that revoked or amended five earlier executive actions, lifting economic sanctions against Iran that have crippled the nation’s economy for years. The European Union and the United Nations also removed sanctions against the country.  

“We’ve achieved this through diplomacy without resorting to another war in the Middle East,” Obama said.

The administration imposed new sanctions, however, against some Iranian citizens and companies in response to Tehran’s recent testing of ballistic missiles, which U.S. officials say violate United Nations resolutions.

Obama said negotiations on the nuclear deal sped up talks on other matters, like Iran’s imprisonment of several Americans. Four Americans were released Saturday and will make their way to the U.S. Sunday as part of a prisoner swap between the two nations. They were Jason Rezaian, a Washington Post reporter who was captured in July 2014 and convicted of espionage last year; Amir Hekmati, a former U.S. Marine captured in 2011 and sentenced to death for espionage in 201; Saeed Abedini, a Christian pastor held by Iran since 2012; and Nosratollah Khosravi-Roodsari, whom the administration only identified as a hostage this weekend. A fifth American, Matthew Trevithick, a researcher imprisoned for 40 days, was released separately of the swap; his name was also not previously reported.

As part of the swap, Obama granted clemency to seven Iranians indicted or imprisoned violating U.S. sanctions against Iran, which he described Sunday as “a one-time gesture to Iran, given the unique opportunity offered by this moment and the larger circumstances at play.” The U.S. also dropped cases against 14 other Iranians it sought to extradite from other countries.

Obama said Iran has agreed “to deepen our coordination” in the search for Robert Levinson, a former FBI agent who disappeared in Iran in 2007, and who,according to his family members, was part of the discussion that led to the prisoner swap. The president also announced that the two nations had reached a settlement on a financial dispute dating back to the 1980s that would save the U.S.“billions of dollars.” As part of this resolution, the U.S. will send back $400 million to Iran, plus $1.3 billion in interest, according to ABC News.

Obama said that, despite the prisoner swap and the implementation of the nuclear deal, “there are profound differences” between the two countries. Various U.S. sanctions against Tehran remain in place, and Iran remains on the State Department’s list of state sponsors of terrorism.

Obama’s remarks on Sunday close out a big week for U.S.-Iran relations, which have come a long way since the U.S. joined talks on Iran’s program for the first time in 2008 under the Bush administration. On Tuesday, the Iranian military detained 10 U.S. sailors on two small Navy vessels that had crossed into Iranian waters in the Persian Gulf, prompting critics of closer U.S.-Iran ties to accuse Iran of aggression. But the situation was resolved within 24 hours by diplomats on both sides, and the sailors were allowed to go on their way.

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