U.S. airstrikes on Thursday in Yemen killed a former detainee at the Guantanamo Bay military prison, Yasir al-Silmi, who was released from the detention center in 2009 by the Obama administration.
Pentagon spokesman Capt. Jeff Davis said on Monday that al-Silmi returned to terrorist activities after being held at Guantanamo from 2002 to 2009, Fox News reported.
Al-Silmi's death came as the U.S. has launched over 40 airstrikes over the course of five nights in Yemen.
The Pentagon and intelligence community have estimated that about 30 percent of detainees transferred from Guantanamo have returned to terrorist activities.
Former President Barack Obama tried to speed the release of Guantanamo detainees towards the ends of his administration, raising the ire of congressional Republicans. Rep. Ed Royce (R., Calif.), chairman of the House Foreign Affairs Committee, called in January for the Obama administration to "immediately halt" moving prisoners from Guantanamo to the custody of foreign governments, citing intelligence indicating that several released detainees sought to return to terrorism.
Some former detainees took high-level positions in terrorist organizations after leaving Guantanamo, like Ibrahim al Qosi, who became the face of al Qaeda in the Arabian Peninsula, Fox News noted.
Another former, Guantanamo detainee, Ayrat Nasimovich Vakhitov, took part in the June 2016 attack on Istanbul's Ataturk airport after his release in 2004.
"Your efforts to close the detention facility at Guantanamo Bay cannot come at the expense of U.S. national security," Royce wrote to Obama earlier this year.
President Trump has pledged to keep the military prison open and fill it with more suspected terrorists.