The White House has vowed to find a former FBI agent who mysteriously disappeared a decade ago in Iran.
Robert Levinson, who disappeared while visiting Iran's Kish resort island in 2007, was not among five Americans freed by Iran in a prisoner exchange last year after sanctions over its nuclear program were lifted.
Levinson was working for the CIA at the time of his disappearance.
"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," White House spokesman Sean Spicer said on March 9.
For several years, U.S. officials have believed Levinson was no longer in Iran, and as part of the prisoner exchange last year secured a commitment from the Iranians to help locate him,
The last public sign that Levinson was alive came in 2011, when the White House received indications that he was being held in Southwest Asia.
At the time, Secretary of State Hillary Clinton publicly asked for his return and the Iranian government offered assistance in finding him.
The U.S. government has offered a $5 million reward for information leading to his return.