_ The Air Force and the Navy are both involved in discussions because Guantánamo detainees would be flown to the Charleston Air Force Base and then transported to the Navy brig 12 miles away. The air base has more room for administrative staff than the naval facility.

_ Discussions focused on the number of support staff that would be needed to provide sufficient security and logistical aid for holding six to 10 Guantánamo detainees in the brig at the Naval Weapons Station in Charleston.

_ Detainees could be held in Charleston for military commission trials there or elsewhere. They might include al-Nashiri, who allegedly devised the plan to blow up the USS Cole.

The sprawling Naval Weapons Station takes up 35,000 acres, with its headquarters located in Charleston and the brig based in Hanahan.

The new details were disclosed by Sen. Jim DeMint and by Senate aides in separate interviews. They cautioned that no final decision has been made and that other military bases on the U.S. mainland are being considered as destinations for some of the 215 detainees now at Guantánamo.

Pentagon officials had previously named the Charleston brig, Fort Leavenworth in Kansas and Camp Pendleton in California as potential sites for the detainees.

"We do not want some of the most dangerous people in the world transferred to American soil, and certainly not to a facility like we have in Charleston, which is a minimum-security facility," DeMint said.

The Pentagon classifies the Consolidated Naval Brig as a "medium-security" prison.

Two days after taking office, Obama issued an executive order pledging to close the Guantánamo prison within a year.

The 2009 Military Commissions Act, which Graham helped craft, requires the president to give Congress at least 45 days' advance notice of transfer of any detainees from Guantánamo.

That deadline is approaching if Obama is to meet his goal of closing the Guantánamo prison by Jan. 22, the one-year anniversary of his executive order.

"It is clear that the wheels are in motion to move terrorist suspects to American soils," Brown said. "We have an obligation to protect Americans from these dangerous individuals. It is disconcerting that the Naval Consolidated Brig is being considered as a possible location for Guantánamo detainees to face trial."

Carol Rosenberg of the Miami Herald contributed to this article.