WASHINGTON — President Barack Obama today began overhauling U.S. treatment of terror suspects, 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 U.S. 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 Guantánamo for 120 days pending a review of the military tribunals.

In other actions, Obama:

4 Created a task force that has 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 because Guantánamo is closing.

• Required all U.S. personnel to follow the U.S. 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 Capitol Hill 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 today.