President Donald Trump pressured Iran Sunday to release ex-FBI agent Robert Levinson, who has been unaccounted for since 2007. Levinson went missing after conducting an unauthorized mission in the country.

“If Iran is able to turn over the U.S. kidnapped former FBI Agent Robert A. Levinson, who has been missing in Iran for 12 years, it would be a very positive step. At the same time, upon information & belief, Iran is, & has been enriching uranium. THAT WOULD BE A VERY BAD STEP!” Trump wrote on Twitter Sunday.

Iran is now acknowledging Levinson’s case, according to documents obtained by NBC News. Moreover, the country acknowledged in a filing to the United Nations that the case was “on going.”

The theocratic regime later argued that the filing is merely a “humanitarian case” and not a “criminal case.” A Trump administration official however, called Iran’s claim “nothing short of a sham,” in a statement to NBC.

The family also confirmed that Iran had the open case and is still holding out hope.

“We welcome Iran’s taking the first step to finally end this nightmare. Now it is time to send him home to us,” Levinson’s family told NBC News Saturday.