More than a decade has passed since Michael Moore released his pro-gun control documentary Bowling for Columbine, and the director says he's saddened that the nation has not made enough strides toward ending violence in schools.

"I never thought I would have to, a decade later, stand here and say that that film of mine did no good. That to me is personally heartbreaking," Moore said while on the red carpet at the National Board of Review Awards.

His 2002 documentary, which won an Academy Award, was inspired by the 1999 Columbine High School shootings in Colorado.

Moore says he has no interest in making a film about last month's shooting at the Sandy Hook Elementary School in Newtown, Connecticut, that left 20 children and six adults dead.