The White House on Thursday expressed its “unwavering” commitment to locate and return ex-FBI agent Robert Levinson, who disappeared 10 years ago on Iran’s Kish Island, and offered a $5 million reward for his “location and safe return.”

“The Trump Administration remains unwavering in our commitment to locate Mr. Levinson and bring him home. We want him back, and we will spare no effort to achieve that goal,” the White House said of the Jewish-American operative and ex-CIA contractor who went missing in March 2007. His whereabouts have been yet another source of friction between Tehran and Washington.

Earlier this week, The New York Times reported that Levinson’s family had appealed to US President Donald Trump to help locate and return him.

In the week of Levinson’s 69th birthday, his family called on Trump to make good on a campaign rally promise in 2015 on Capitol Hill where he said: “If I win the presidency, I guarantee you that those four prisoners are back in our country before I ever take office. I guarantee that.”

He was referring to four Americans held by Iran, Levinson, Saeed Abedini, Amir Hekmati and Jason Rezaian. Abedini, Hekmati and Rezaian were released in a controversial deal with Iran last year, but Levinson’s whereabouts remain unknown

President Barack Obama’s White House had suggested that Levinson may no longer be in Iran.

The Trump White House has taken a more hardline stance against Tehran and on Thursday called for information and plugged a five million dollar reward for his “location and safe return.”

“The Levinson family has suffered far too much during the last decade due to the absence of Mr. Levinson, a loving father, brother, husband, grandfather, and friend to many,” the White House said.

“Each and every day, but especially today, our hearts are with the Levinson family. We will not rest until this case is resolved,” it said.

Still image from a November 2010 video showing Robert Levinson, which was received by his family. (YouTube: Help Bob Levinson)

Still image from a November 2010 video showing Robert Levinson, which was received by his family. (YouTube: Help Bob Levinson)

A 2013 Associated Press investigation found that Levinson was working for the CIA on an unauthorized intelligence-gathering mission to find information about Iran’s nuclear program when he disappeared from Iran’s Kish Island on March 9, 2007.

The 2013 AP investigation showed that in a breach of the most basic CIA rules, a team of analysts — with no authority to run spy operations — paid Levinson to gather intelligence from hotspots around the world, including the Middle East and Latin America.

The official story when Levinson disappeared was that he was in Iran on private business, either to investigate cigarette smuggling or to work on a book about Russian organized crime. It has a presence on Kish, a tourist island.

In fact, he was meeting a source, an American fugitive, Dawud Salahuddin. He is wanted for killing a former Iranian diplomat in Maryland in 1980. In interviews, Salahuddin has admitted killing the diplomat.

The CIA paid Levinson’s family $2.5 million to preempt a revealing lawsuit, and the agency rewrote its rules restricting how analysts can work with outsiders. Three analysts who had been working with Levinson lost their jobs.

Levinson’s family is convinced he is alive and that Iranian authorities know where he is, even as some US officials believe he died in captivity.

He was last seen in a hostage video and a series of photos made in 2010. It was not clear which organization or group was holding him.

Officially, Iran has denied knowing his location.