The Defense Department announced Wednesday prisoners Noor Uthman Muhammed and Ibrahim Othman Ibrahim Idris were transferred to Sudan.
"The United States coordinated with the government of Sudan regarding appropriate security measures and to ensure that these transfers are consistent with our humane treatment policy," the Defense Department said in a statement. "[As of Wednesday], 158 detainees remain at Guantanamo Bay."
Idris was identified as a veteran al-Qaida member who served as a "trusted agent" of Osama bin Laden when the al-Qaida leader lived in Sudan in the 1990s.
Paul Lewis, former general counsel at the House Armed Services Committee, was appointed in October to serve as special envoy for the closure of the military detention center at Guantanamo Bay.
President Barack Obama has said repeatedly he wants to close the detention center.