President Barack Obama began overhauling US treatment of terror suspects Thursday, signing orders to close the Guantanamo Bay detention center, review military trials of suspects and ban the harshest interrogation methods. With three executive orders and a presidential directive signed in the Oval Office, Obama started reshaping how the United States prosecutes and questions al-Qaida, Taliban or other foreign fighters who pose a threat to Americans. The centerpiece order would close the much-maligned US prison at Guantanamo Bay, Cuba, within a year, a complicated process with many unanswered questions that was nonetheless a key campaign promise of Obama's. The administration already has suspended trials for terrorist suspects at Guantanamo for 120 days pending a review of the military tribunals. In other actions, Obama: -Created a task force that would have 30 days to recommend policies on handling terror suspects who are detained in the future. Specifically, the group would look at where those detainees should be housed since Guantanamo is closing. -Required all US personnel to follow the US Army Field Manual while interrogating detainees. The manual explicitly prohibits threats, coercion, physical abuse and waterboarding, a technique that creates the sensation of drowning and has been termed a form of torture by critics. However, a congressional aide says that the administration also is planning a study of more aggressive interrogation methods that could be added to the Army manual _ which would create a significant loophole to Obama's action Thursday. -Directed the Justice Department to review the case of Qatar native Ali al-Marri, who is the only enemy combatant currently being held on US soil. The review will look at whether al-Marri has the right to sue the government for his freedom, a right the Supreme Court already has given to Guantanamo detainees. The directive will ask the high court for a stay in al-Marri's appeals case while the review is ongoing. The government says al-Marri is an al-Qaida sleeper agent. An estimated 245 men are being held at the US naval base in Cuba, most of whom have been detained for years without being charged with a crime. Among the sticky issues the Obama administration has to resolve are where to put those detainees - whether back in their home countries or at other federal detention centers - and how to prosecute some of them for war crimes.