Please answer the following question: Generate a question about the following movie plot: In 1969, during the Vietnam War, Army Special Forces Colonel Walter E. Kurtz (Marlon Brando) has become insane and now commands his own Montagnard troops, inside neutral Cambodia, as a demi-god. Colonel Lucas (Harrison Ford) and General Corman (G.D. Spradlin), who are growing increasingly concerned with Kurtz's renegade operations, assign U.S. Army Captain and Studies and Observations Group veteran Benjamin L. Willard (Martin Sheen) to terminate the Colonel's command with extreme prejudice. Willard, while ambivalent about the mission, joins a Navy PBR (for "Patrol boat, riverine") commanded by "Chief" (Albert Hall) and crewmen Lance (Sam Bottoms), "Chef" (Frederic Forrest) and "(Mr.) Clean" (Laurence Fishburne) to head upriver. They rendezvous with surfing enthusiast Lieutenant Colonel Bill Kilgore (Robert Duvall), a commander of a cavalry squadron, to discuss going up the Nung River. Kilgore initially scoffs at them, but befriends Lance when he discovers he is an expert surfer and agrees to escort them through the Viet Cong-held coastal mouth of the river where surfing conditions are particularly good. At dawn the helicopter raid commences. Amid the attack, Kilgore calls in a napalm sortie on the local cadres and the rivermouth is taken. Willard gathers his men to the PBR, which has been transported via helicopter, and begins the journey up river. Tension arises between Chief and Willard as Willard believes himself to be in command of the PBR while Chief prioritizes other objectives over Willard's secret mission. Slowly making their way upriver, Willard reveals part of his mission to the Chief to assuage the Chief's concerns about why his mission should take precedence. As night falls, the PBR reaches the chaotic last US outpost on the Nung River, the Do Long Bridge. Willard and Lance enter the base seeking information on what is upriver. Unable to find anyone in command of the base, Willard orders the Chief to continue upriver as an unseen enemy launches a strike on the bridge. The next day, Willard learns...
A:
Who plays Colonel Lucas?