(CNN) -- Veteran director Barry Levinson has been tapped to direct a "political thriller" based on the 1995 bombing of a federal courthouse in Oklahoma City. Sources with knowledge of the project say the tentative title of the film is "O.K.C." The script is being written by Clay Wold and is based on the story of his brother, who was a young legal clerk on the defense team for Timothy McVeigh. Among Levinson's directing credits are "Good Morning, Vietnam," "The Young Sherlock Holmes" and "The Natural." Oklahoma City was the site of the worst terrorist attack on U.S. soil before September 11, 2001. The 1995 bombing of the state capital's federal building left 168 dead. McVeigh, a white supremacist anti-government activist and former U.S. soldier, was executed for the attack in 2001. CNN's Douglas Hyde contributed to this report .
Oklahoma City is the site of the worst terrorist attack on U.S. soil before September 11, 2001 . The 1995 bombing of the state capital's federal building left 168 dead . The tentative title of the film is "O.K.C.," sources with knowledge of the project say .