After initially cooperating then going silent after being read his Miranda rights, Umar Farouk Abdulmutallab had been under pressure from the FBI and the Justice Department to resume talking, a source told Politico.
"It started last week, and has continued for several days," the source said.
With Abdulmutallab now answering questions, the source said: "The information has been active, useful, and we have been following up. The intelligence is not stale. He certainly sees that there are incentives provided by the criminal justice system to cooperate."
The incentives can include a reduced sentence, Politico said.
Abdulmutallab, a Nigerian man being held in a federal prison outside Detroit, was questioned by the FBI for 50 minutes on the day of the attack, then read his rights, the Washington publication said
Also Tuesday, FBI Director Robert Mueller told the Senate Abdulmutallab spoke freely to agents after his arrest until undergoing surgery for leg burns, NBC News reported. After surgery he said he wouldn't answer more questions. Convinced he would not, agents told him of his right to remain silent, Mueller said.
NBC reported Abdulmutallab's cooperation could signal his preparing to plead guilty, which could spare him death.
Some critics say Abdulmutallab should have been treated not as a criminal defendant afforded rights such as the Miranda warning but as an enemy combatant to be questioned by intelligence officers.