A 26-year-old Massachusetts man with a physics degree was arrested and charged Wednesday with plotting an attack on the Pentagon and the U.S. Capitol with a remote-controlled model aircraft, authorities said.

Rezwan Ferdaus, a U.S. citizen from Ashland, Mass., planned to use model aircraft filled with C-4 plastic explosives, authorities said.

As a result of an undercover FBI investigation, Ferdaus, who has a physics degree from Northeastern University in Boston, was charged with attempting to provide material support and resources to al-Qaida for attacks on U.S. soldiers overseas, authorities said.

His federal public defender couldn’t be reached immediately for comment.

A law enforcement official said Ferdaus posed no immediate danger to the public because undercover operatives kept in close contact with him.

“There is no information to indicate he was connected to a foreign terrorist organization. It appears he was radicalized watching videos on the Internet. He was given the opportunity to back down, but he never wavered” from his intention to carry out the attacks, the source said.

The investigation also involved a cooperating witness, and authorities began recording conversations between that witness and Ferdaus in January, authorities said.

Ferdaus began planning a violent “jihad” against America in early 2010, authorities said, and he began supplying the FBI undercover agents with cell phones rigged to act as electric switches for improved explosive devices, intended to be used to kill U.S. soldiers overseas.

Undercover federal agents also gave Ferdaus 25 pounds of fake C-4 explosives. Only a very small amount of it was the real thing, the source said.

The FBI agents also gave Ferdaus six AK-47 assault rifles and three grenades, but they weren’t functional, the source said.

Between May and this month, Ferdaus also ordered and acquired a $6,500 remote-controlled aircraft, an F-86 Sabre, that he kept in a rented storage facility in Framingham, Mass., that he maintained under a false name, authorities said.

Despite coming into possession of the plane, another law enforcement official said, “The person was never really a threat.”

Ferdaus is unmarried with no children, authorities said.

A federal magistrate in Worcester, Mass., on Wednesday ordered Ferdaus to be held until Monday, when a detention hearing is scheduled, authorities said.

CNN’s Carol Cratty and Michael Martinez contributed to this report.