With a transfer and release program gaining steam, the number of detainees in U.S. custody in Iraq has fallen to its lowest point since November 2005, officials said this week.

According to officials with Task Force 134 — the command responsible for detainee operations in Iraq — there are now 11,999 detainees being held by U.S. forces throughout the country. At one time during the "surge" of U.S. forces, that number was as high as 26,000.

Under a provision of the security agreement signed between Iraq and the United States, all detainees are to be released or transferred to Iraqi control. The goal, according to Task Force 134, is ending the coalition detainee operations mission in Iraq.

Under an agreement reached by a committee of Iraqi and American officials, the U.S. military has pledged to release or transfer 1,500 detainees each month — an average of 50 per day — until their facilities are empty. The vast majority of detainees are held at Camp Cropper in Baghdad and Camp Bucca in southern Iraq.

Since January, some 3,271 detainees have been released, officials said this week. Another 2,325 have either been convicted or are under trial in Iraqi courts.

Of the 4,500 "low threat" detainees considered for release so far under the agreement, around 400 have been ordered held by Iraqi officials because they are still considered security threats, officials said.

Iraqi authorities review detainees’ case files before a determination is made on their status. The Iraqis can ask for custody of the detainee, or the person can be released outright.

In recent years, the U.S. detention system in Iraq has undergone several makeovers to change the image created by the Abu Ghraib detainee abuse scandal. Officials have stressed vocational and religious programs aimed at reducing recidivism. They have also touted the increased pace of releases and transfers to Iraqi authorities.

Task Force 134 officials have also sought to reassure troops in the field that targets they detain will not be released without going through a review. Troops now have stringent requirements on gathering evidence against detainees, and U.S. officials have estimated that there are around 5,000 "hard-core" detainees they would not want to see released by the Iraqis.