Jose Pimentel, a follower of late Muslim cleric Anwar al-Awlaki, was arraigned on Sunday on terrorism-related charges.
A US citizen born in the Dominican Republic, Pimentel was arrested on Saturday in a Manhattan apartment while assembling a bomb.
“We had to act quickly because he was in fact putting this bomb together,” said Police Commissioner Ray Kelly.
Pimentel admitted he “took active steps to build the bomb, including shaving the match heads and drilling holes in the pipes” and was “one hour away from completing it,” said the criminal complaint filed by the Manhattan District Attorney.
Authorities called him a “lone wolf” who had converted to Islam and became a radical.
Pimentel faces life in prison if convicted.