Iran has taken another American citizen captive. On Tuesday, Iran’s state-owned IRIB news network announced that the regime had arrested Nizar Ahmad Zakka, a Lebanese-American from Riverside, California with alleged “deep ties” to the U.S. military and intelligence services on suspicion of espionage.

Zakka, the Secretary General of the Arab Information and Communications Technology Organization (IJMA3), had traveled to Tehran on September 14 to attend a conference called “Entrepreneurship & Employment.”

According to a statement signed by Lebanese lawyer Antoine Abou Dib on behalf of the Washington, D.C.-based organization IJMA3, Zakka had received an invitation from the Vice President of Women and Family Affairs of the Islamic Republic of Iran to attend the 2nd International Conference & Exhibition on Women in Sustainable Development, where he was a featured speaker.

On September 18, 2015, Zakka reprotedly left his Tehran-based hotel to return to Beirut. However, he neither boarded his flight nor arrived in Lebanon as planned.

The report by Iran’s Press TV notes that the IRIB report featured photographs of Zakka in military uniform at a U.S. base in Riverside County, California and that several sources labeled Zakka as “a hidden treasure trove” as a result of his connections with U.S. intelligence and military.

Zakka’s disappearance comes just days after the Iranian Revolutionary Guard Corps (IRGC) arrested Iranian-American citizen Siamak Namazi. Names is one of the founders of the National Iranian American Council (NIAC), a Washington, D.C.-based lobbying group that has been accused of working in support of the Iranian regime. He was taken to Evin prison, which is known for its horrific mistreatment of prisoners.

So far the fates of Washington Post journalist Jason Rezaian, former US marine Amir Hekmati, and Pastor Saeed Abedini remain unknown as they languish in prison. Siamak Namazi and Nazar Zaka now bring the total five American prisoners in Iran. (American Robert Levinson’s whereabouts are still a mystery since his disappearance on Iran’s Kish Island in 2007. Iran says it does not know where he is.)

On Tuesday, House Foreign Affairs Committee Chairman Ed Royce (R-CA) denounced the lack of action the Obama administration has taken to bring back Americans jailed in Iran as well as to secure the status of Americans in the Islamic Republic.

Responding to reports of Zaka’s arrest, Royce said, “[A]nother day, another hostage taken by Iran. Iran has clearly declared open season on anyone with ties to the United States. What is the White House going to do about it?”

November 4 marks the 36-year-anniversary of the infamous 1979 Iranian hostage crisis.

Follow Adelle Nazarian on Twitter @AdelleNaz and on Facebook.