Authorities say Rezwan Ferdaus, 26, planned to use remote-controlled aircraft packed with plastic explosives.
Ferdaus, a physics graduate from Northeastern University, was arrested in Framingham outside Boston after undercover federal agents delivered materials he had allegedly requested, including grenades, six machine guns and what he believed was 24 pounds of C-4 explosive.
The FBI began its investigation last year after Ferdaus allegedly contacted a federal informant about his plan to wage "jihad" against the U.S. He allegedly said he was becoming convinced America was evil.
According to a federal affidavit, Ferdaus met with undercover agents, who he thought were members of al Qaeda, to discuss his plot.
The planes, guided by GPS and capable of speeds greater than 100 mph, would hit the Pentagon and blow the Capitol dome to "smithereens," according to Ferdaus' plan, detailed in the affidavit. Ferdaus then planned a follow-up attack with six people divided into two teams, all armed with automatic weapons, according to the affidavit.
Ferdaus allegedly drew up a 15-phase attack plan and rented storage space to work on the planes in Framingham. He allegedly supplied the undercover agents with cellphone devices he said could be used to remotely detonate explosives.
When the undercover agents falsely told him the devices had been used to kill three U.S. soldiers in Iraq, he allegedly became visibly excited and said he felt "incredible."
"We're changing the world," he allegedly said.
Ferdaus made a brief initial appearance Wednesday in federal court on charges of attempting to destroy federal buildings and providing support to a foreign terrorist organization, al Qaeda. A detention hearing was scheduled for Monday.
The Associated Press contributed to this report.