U.S. Secretary of State John Kerry talks to reporters about his negotiations with Iran upon his arrival from Vienna at Andrews Air Force Base, Md., on Sunday.

VIENNA — Four Americans and seven Iranians got tickets to freedom in a prisoner swap playing out alongside the kick-start of an accord lifting heavy international sanctions on Iran in return for its agreement to pull back its nuclear program. A fifth American was released separately.

The negotiated exchange eases one leading irritant as the two countries gingerly explore prospects for a smoother relationship after decades of hostility — even as they remain sharply at odds on other fronts.

Washington Post reporter Jason Rezaian, former U.S. Marine Amir Hekmati, pastor Saeed Abedini and Nosratollah Khosravi-Roodsari, whose name had not been previously made public, were freed from custody in Iran and were to be flown to Switzerland, U.S. officials said. U.S. student Matthew Trevithick was released independently of the exchange on Saturday and already was on his way home.

In turn, the U.S. will pardon or drop charges against seven Iranians — six of whom are dual U.S.-Iranian citizens — accused or convicted of violating U.S. sanctions.

Three were serving prison terms and now have received a commutation or pardon. Three others were awaiting trial; the last one made a plea agreement.

It's unclear if they will leave the U.S. for Iran. They are free to stay in the United States.

In addition, the U.S. will drop Interpol “red notices” — essentially arrest warrants — on 14 Iranian fugitives it has sought, officials said.

The announcement of the exchange came shortly before Iran was certified as having met all commitments under the nuclear deal with six world powers.

U.S. Secretary of State John Kerry, Iranian Foreign Minister Mohammad Javad Zarif and other officials involved in the accord met in Vienna as the diplomatic achievement unfolded.

The release of the prisoners and the nuclear deal developments capped weeks of intense U.S.-Iran diplomacy that took several unexpected turns after an Iranian ballistic missile test in October and then the detention on Jan. 12 by Iran of 10 U.S. Navy sailors and their two boats in the Persian Gulf.

The four Americans were still in Iran Sunday as arrangements progressed to get them out, said a senior Obama administration official.

Robert Levinson, who disappeared in Iran in 2007 while working for the CIA on an unapproved intelligence mission, wasn't part of the deal. American officials are unsure if the former FBI agent is even still alive. The Iranians have always denied knowing his location.