Umar Farouk Abdulmutallab, the 23-year-old Nigerian accused of trying to destroy a US airliner on Christmas Day, made his first court appearance on Friday.
He pleaded not guilty to a foiled attack that has provoked an extensive review of US intelligence and airport security.
His arraignment in a Detroit federal court came after a grand jury indicted Mr Abdulmutallab this week on six charges, including the attempted use of a weapon of mass destruction to kill nearly 300 people on board Northwest Airlines flight
253, which carries a life sentence.
He is alleged to have hidden a cocktail of explosive materials in his underpants when he boarded the flight from Amsterdam to Detroit.
Some Republicans have criticised the Obama administration for allowing the suspect the benefit of a criminal trial rather than treating him as an enemy combatant.
There was speculation that the Nigerian’s lawyers might attempt to secure a plea bargain in exchange for information he could give
about his al-Qaeda connections.
US president Barack Obama has rebuked the US intelligence community for having elements of information that could have prevented the bomb plot
but then failing to “connect the dots”.