(CNN) Five Guantanamo Bay detainees have been transferred, the Department of Defense announced in a press release Wednesday.

Al Khadr Abdallah Muhammad Al Yafi, Fadel Hussein Saleh Hentif, Abd Al-Rahman Abdullah Au Shabati and Mohammed Ahmed Salam were sent to Oman. Akhmed Abdul Qadir was transferred to Estonia.

It is believed to be the first time either country has accepted Guantanamo Bay transfers.

The detainees were not released to their home country of Yemen because the government there -- under pressure from al Qaeda and Houthi militants -- cannot ensure they won't join al Qaeda elements. The United States has been trying to find countries to take on the detainees who will provide security and human rights assurances for them.

There are currently 122 prisoners left at Guantanamo Bay, including 79 Yemeni men, according to documents from the Pentagon and Joint Task Force Guantanamo.

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