Rezwan Ferdaus, 26, of Ashland entered his plea in U.S. District Court in Boston Friday. While sentencing won't be until November, he is expected to spend 17 years in prison followed by 10 years of supervised release, the Boston Herald reported.
Ferdaus pleaded guilty to two of the six counts federal prosecutors lodged against him.
Dressed in beige prison scrubs, and sporting a long goatee and stringy beard, Ferdaus smiled at his family at least twice as they shouted "we love you" at the beginning and end of the hearing, the newspaper said.
Ferdaus was arrested in September. The Boston Globe said FBI agents posing as al-Qaida recruiters conducted a nine-month undercover investigation that led to accusations Ferdaus had modified a dozen cellphones into control switches for improvised-explosive devices that would be used to kill U.S. military personnel.
Federal documents showed investigators learned Ferdaus planned to launch three remote-controlled planes, each about 5 feet long and packed with explosives, into federal buildings. Prosecutors say a six-man team was to shoot anyone who fled the buildings.
The Globe said undercover FBI agents gave Ferdaus money to buy the planes, explosives, three grenades and six AK-47 assault rifles. Authorities said he was arrested after he locked the explosives and guns in a Framingham storage facility he rented.
Ferdaus' defense attorneys had contended he is mentally ill.