A 26-year-old Massachusetts man was busted yesterday in a bizarre plot to attack the Pentagon and US Capitol with remote-controlled model planes packed with explosives.

Rezwan Ferdaus, a US citizen, was radicalized by watching jihadist Web sites and planned to kill “enemies of Allah” in an elaborate plot hatched a year ago, according to the Justice Department.

But the collaborators he thought were al Qaeda recruiters turned out to be undercover FBI agents and they arrested him yesterday after he took possession of his arsenal — including grenades, six AK-47 assault rifles and what he believed were 25 pounds of C-4 explosives.

Ferdaus, a graduate of Northeastern University with a degree in physics, began talking last December with an ex-con about attacking the Pentagon with small “drone airplanes” guided by GPS equipment to “decapitate” the military.

The ex-con, who was working with the feds, and the undercover agents recorded numerous talks in which Ferdaus elaborated on his plan, which also involved blowing the dome of the Capitol “to smithereens.”

He planned to launch the model planes from near the Jefferson Memorial, and at one time set July 5, during the Independence Day weekend, as the date.

In March he told the agents that he conducted some of his research “in a way that’s more secure” in New York, apparently at an Internet cafe.

Ferdaus, of Ashland, Mass., also bought cellphones, removed the back covers and soldered wires to each phone in order to turn them into an electrical switch for improvised explosive devices to be used in Iraq.