A formal review process for dozens of men being held at Guantanamo Bay without charge has begun as part of an effort to close the prison, the Pentagon said Wednesday. Officials from several government agencies, including the State Department and Department of Homeland Security, will re-evaluate previous determinations that some of the men held on the U.S. base in Cuba are too dangerous to release, the Defense Department said in a statement. The U.S. has not yet said how many of the 164 prisoners now at Guantanamo will be reviewed. More than 80 have already been cleared for release or transfer but are still held either because of restrictions on releases imposed by Congress or because they are from Yemen, which is considered too unstable to take former prisoners. The government previously said that about 46 prisoners are being held in indefinite detention under international law. Those receiving a review would include this group. The men will be represented at a hearing by a military officer but can also hire a lawyer as well.