Martin Baron, executive editor of The Washington Post, reiterated his call for the release of correspondent Jason Rezaian, whose arrest and year-long detention in Iran drew fresh attention with the country’s nuclear agreement with the United States and other world powers last week.

Baron, appearing Sunday on CNN’s “Reliable Sources,” declined to say whether the fate of Rezaian and other Americans being held by Iran should have been tied to the deal to limit Iran’s nuclear program. But he said he took the Obama administration at its word that it is continuing to work for Rezaian’s release.

“We hope that’s the case . . . and we want them to work harder,” Baron said, adding that The Post also has been working to secure Rezaian’s release. “We’ve tried every channel we can think of — through other governments, through individuals, through the administration — you name it. We’ve tried every channel we believe is available to us.”

Rezaian was arrested in July 2014, but it wasn't until April that Iran stated that he would face trial on espionage and other charges. Rezaian, who is an accredited journalist in Iran, has denied the allegations.

At a White House news conference last week during which President Obama talked about the nuclear agreement, CBS News correspondent Major Garrett asked the president, “Why you are content with all the fanfare around this deal to leave the conscience of this nation, the strength of this nation, unaccounted for in relation to these four Americans” whose fate is unknown?

Obama took umbrage at the question and said his administration is "working diligently to try to get them out.”

Although never formally tied to the nuclear talks, U.S. negotiators have always maintained that they raised the issue of the four Americans on the sidelines of every meeting with the Iranians. Secretary of State John Kerry has said that at his last meeting with Iranian Foreign Minister Mohammad Javad Zarif, just before they publicly announced the deal, he again pressed the matter of the four, who include Amir Hekmati, a Marine veteran from Flint, Mich.; Saeed Abedini, a pastor from Boise, Idaho; and Robert Levinson, a former FBI agent who has been missing since a 2007 trip to Iran.

Asked by host Brian Stelter whether he considered Rezaian to be a hostage, Baron stopped short of agreeing with that characterization.

“I think that’s the question. Why is he being held? What are the conditions being placed on his release? What are the Iranians expecting in exchange for his release?” Baron said, adding that the answers to those questions would determine whether the term "hostage" was appropriate.

He suggested that more important than the terminology is the fact that Rezaian “is being held unjustly and has been held unjustly for a full year now.”

Jason Rezaian’s journey has taken him from a childhood in San Francisco to his father’s native Iran. At 37, he became the Washington Post correspondent in Tehran. In July 2014, he was thrown into Iran’s Evin Prison, where he remains. This is his story. (Jorge Ribas/The Washington Post)

Carol Morello contributed to this report.