Trump demanded the return of Robert Levinson, an American former law enforcement officer who disappeared in Iran more than a decade ago, as well as businessman Siamak Namazi and his father, Baquer.

Washington slapped new economic sanctions against Iran over its ballistic missile program last Tuesday, and said Tehran’s “malign activities” in the Middle East undercut any “positive contributions” coming from the 2015 nuclear accord.

The Trump administration is putting pressure on Iran, while keeping in place the nuclear deal between Tehran and six world powers that curbs its nuclear program in return for lifting economic sanctions.

Trump and his administration are “redoubling efforts” to bring back all Americans unjustly detained abroad, like 46-year-old Siamak Namazi and his 80-year-old father Baquer Namazi, who each were sentenced by an Iranian court to 10 years in prison on charges of spying and cooperating with the United States.

In October of 2015, Iran’s Islamic Revolutionary Guard Corps detained Siamak in while he was visiting family in Tehran, and his father, a former Iranian provincial governor and former UNICEF official, was arrested in February of last year, family members said.

The U.S. government has a $5 million reward for information leading to Robert Levinson’s safe return. He is a former agent for the Federal Bureau of Investigation and for the Drug Enforcement Administration, who disappeared in Iran in 2007.

Iran’s judiciary spokesman said on Sunday that Xiyue Wang, a Chinese-born U.S. citizen graduate student from Princeton University, was sentenced by an Iranian court to 10 years in jail on spying charges.

“Iran is responsible for the care and wellbeing of every United States citizen in its custody,” the White House said in the statement.

In a related effort on Friday, Rex Tillerson, U.S. Secretary of State, met with Yusuf bin Alawi, foreign affairs minister of Oman, an Arab country on the southeastern coast of the Arabian Peninsula. In the past, Washington has sought Oman’s mediation to help in securing the release of detained Americans abroad. Oman paid the bail that ultimately resulted in the release of three American hikers in 2010 and 2011, and last year, American prisoners held captive by Yemen Houthi rebels were released after Oman’s intercession.