The White House on Tuesday pressed Iran to return a former FBI agent — missing for six years — to the United States, seeking to use momentum from a newly struck deal over the Middle Eastern nation's nuclear program to score another long-sought diplomatic victory.

The U.S. government believes Robert Levinson was abducted during a business trip to Iran in 2007, making him one of the longest-held American hostages in history.

“As we approach the upcoming holiday season, we reiterate the commitment of the United States government to locate Mr. Levinson and bring him home safely to his family, friends, and loved ones,” the White House said in a statement Tuesday. “We welcome the assistance of our international partners in this investigation, and we respectfully ask the government of the Islamic Republic of Iran to assist us in securing Mr. Levinson’s health, welfare and safe return.”

Just two days ago, the U.S., among other nations, struck a deal with Iran that eases economic sanctions on the longtime American rival in exchange for the Iranian regime slowing some key nuclear developments.

The White House is framing the preliminary deal as a way to strike a long-term accord that would keep Iran from building a bomb. And U.S. diplomats are hoping to use the renewed talks between the nations to facilitate progress in other areas, including the return of Levinson to American soil.

Levinson, a father of seven, disappeared during a trip to Iran’s Kish Island. Levinson’s family says they were sent a hostage video and emailed photos of the former FBI agent in recent years.