A former Gitmo detainee connected to last month’s ISIS attack on the Istanbul airport that killed 45 and injured more than 230 others was officially added to the U.S. government’s list of designated terrorists Wednesday.

The State Department confirmed to Fox News that Ayrat Nasimovich Vakhitov was at the Guantanamo detention camps from June 13, 2002 until his transfer to Russia by the Bush administration in 2004.

“For an individual to be designated a terrorist by our State Department, the threshold is way high,” Tony Shaffer, a former defense intelligence officer , told Fox. “The Pentagon has been very reluctant to release a number of individuals and has had to bow to White House and State Department pressure.”

The State Department’s announcement of the terrorist designation does not say Vakhitov was once held at Gitmo, nor does it cite his reported ties to the June attack in Turkey. The connection was first reported by the Long War Journal and independently confirmed by Fox.

On July 5, Voice Of America reported , citing a source inside the small North Caucasus Muslim community in Turkey, that Vakhitov was among 30 people arrested in connection with the June 28 Istanbul airport attack. VOA reported there was no confirmation from Turkish authorities.

According to a leaked Joint Task Force – Guantanamo threat assessment of Vakhitov, he was arrested and jailed “by the Taliban on suspicion of espionage,” jailed in Kandahar and eventually transferred to Guantanamo because of “his possible knowledge of an American citizen killed” at that same prison “while he was there.”

Vakhitov is a foreign terrorist fighter from Tatarstan, Russia who has fought in Syria. Vakhitov is associated with Jaysh al-Muhajirin Wal Ansar, a group that was designated by the U.S. Department of State as Specially Designated Global Terrorists. Vakhitov has also used the internet to recruit militants to travel to Syria.

A second individual, Aslan Avgazarovich Byutukaev, also received the terrorist designation Wednesday. The State Department said he leads a group in Chechnya that is tied to the Islamic State’s so-called Caucasus province.

With the designation of Vakhitov as a terrorist, Fox News asked the State Department how policy supporting the closure of Gitmo is consistent with reducing terrorism and national security.

A State Department official did not directly address the question, but said “We take any incidence of re-engagement very seriously... We work in close coordination through military, intelligence, law enforcement, and diplomatic channels to mitigate re-engagement and to take follow-on action when necessary.”