Authorities said the explosives were always under the control of federal agents, and the public was never in danger. Counterterrorism experts and model-aircraft enthusiasts say it would be nearly impossible to inflict large-scale damage using model planes.

Prosecutors have said Ferdaus began planning jihad, or holy war, against the United States in early 2010 after becoming convinced through jihadi websites and videos that America was evil. He later contacted a federal informant and began meeting to discuss the plot with undercover agents he believed were members of Al Qaeda.

Ferdaus was accused of planning to use three remote-controlled planes measuring 60 to 80 inches in length and capable of speeds greater than 100 mph. Each plane, guided by GPS, was to be packed with 5 pounds of explosives.

In court documents, authorities said Ferdaus traveled to Washington to do surveillance and rented storage space to work on the planes in Framingham.