BOSTON — A federal grand jury in Boston has indicted a 26-year-old man for allegedly plotting to use model airplanes to attack the Pentagon and U.S. Capitol, the U.S. Department of Justice said Thursday.

Rezwan Ferdaus, a U.S. citizen from Ashland, Mass., was arrested Wednesday. Authorities said he planned to use large, remote-controlled model aircraft filled with C-4 plastic explosives against the targets.

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 Qaeda for attacks on U.S. soldiers overseas, authorities said.

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 suggesting he was connected to a foreign terrorist organization, the source said, adding he was apparently radicalized by watching videos on the internet.

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 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 September, Ferdaus also ordered and acquired a $6,500 remote-controlled aircraft, an F-86 Sabre, that he kept under a false name in a rented storage facility in Framingham, Mass., authorities said. He also planned to use other remote-controlled models of military aircraft, authorities said.

The models he planned to use are about one-tenth the size of the actual aircraft.

A detention hearing for Ferdaus, who is not married and has no children, is scheduled for Monday.