On 16 January 2016, U.S. officials confirmed a prisoner swap with Iran, which involved the Islamic republic releasing four Iranian-American prisoners in exchange for seven Iranians charged with violating sanctions and trade restrictions. Tehran also released a fifth imprisoned American separate from the prisoner exchange deal and in addition to the seven pardoned criminals, the U.S. will dismiss charges against 14 Iranian fugitives, NPR writes.

The four freed American citizens are: Washington Post correspondent Jason Rezaian, former Marine Amir Hekmati, Reverend Saeed Abedini and Nosratollah Khosravi-Roodsari. The fifth American is Matthew Trevithick.

Some of the—largely considered—trumped-up charges leveled on the four Americans include, but are not limited to: espionage, threatening national security and “collaborating with hostile governments.”

This subject has been a fervently debated issue for months and has often been tied in with the discourse surrounding the nuclear deal with Iran.

Some may well remember the Iran Nuclear Deal press conference that President Obama held on July 15 of last year. The provocative question posed by Major Garrett of CBS News regarding the Americans imprisoned in Iran and the president’s contentment to ignore them—along with President Obama’s scolding response—went on to dominate the subsequent news cycle.

At one point during his castigation of the reporter, President Obama asserted, “I’ve met with the families of some of those folks. Nobody’s content. And our diplomats and our teams are working diligently to try to get them out.” The president then went on to explain how tying the release of the American prisoners to the nuclear deal would weaken the United States’ leverage and make it more difficult to step away from negotiations.

Here’s the full exchange:

It has now come to light that negotiations to free the American prisoners have been in motion for over a year, with the diplomatic efforts now finally coming to fruition. The announcement of the nuclear deal apparently accelerated the dialogue for the prisoner exchange.

As of Sunday, three of the five released Americans have landed in Germany, while Matthew Trevithick is said to have left Iran and Nosratollah Khosravi-Roodsari has decided, of his own accord, to stay in Iran, CNN reports.

The New Yorker writes that, “At least two Americans are not coming home.” Those citizens include Siamak Namazi and Robert Levinson. Levinson is a retired FBI agent who was last seen on Iran’s Kish Island in 2007. A stipulation of the agreement between the United States and Iran ensures that Iranian officials will cooperate with the U.S. in order to discover the whereabouts of Mr. Levinson.

The prisoner swap came on the heels of an international inspection confirming Iran’s compliance with the nuclear deal and, as a result, some of the economic sanctions against Tehran have been lifted.