Stars Ben Affleck and Morgan Freeman mingled with congressmen and CIA officials at this week's world premiere of the action thriller "The Sum of All Fears" in Washington, D.C., reports PEOPLE. Based on a 1991 book by Tom Clancy, the movie depicts a nuclear attack on America by a terrorist group. "I had already watched all the movies and read all the books," said Affleck, 29, who embraced author Clancy, 55, when he stepped on the red carpet. Affleck plays Jack Ryan as a young analyst in a kind of prequel to previous Clancy-based movies, which starred Harrison Ford, 59, and Alec Baldwin, 44, as older incarnations of Ryan. "I consulted Alec and Harrison and Tom Clancy all before going into this," Affleck told PEOPLE, "because I wanted to pay my respect to them for the fine job that they did . . . Also to touch base with those guys and feel like it was kind of a real thing and I was part of that tradition." Still, Affleck calls his performance more than mere mimicry. "The thing about Harrison Ford is, I wouldn't even ask. Harrison Ford is so his own man. There is no other Harrison Ford. There is no next Harrison Ford. If I tried to do what he does, I would only be a pale imitation of Harrison Ford. For me, it was about trying to invent it in a new way so that I could approach it, which is what we did by starting over from the beginning."