The film is scheduled to debut at the Toronto International Film Festival in September.
"I've been very quiet about the making of this film. You probably haven't seen much of me…. We've been very diligent about keeping this under cover," Moore said during a short Q&A, saying the film is "of epic nature."
In an age when almost any information leaks to social media in the blink of an eye, keeping a major project focusing on the US military under wraps is an achievement in itself.
The director of "Bowling for Columbine" (2002) and "Fahrenheit 9/11" (2004) has not provided many details on the new documentary but confirmed that the US' increasing belligerence is at the heart of the new project. It remains unclear whether the film will focus on the post-9/11 era or examine US foreign policy in general.
"The issue of the United States at infinite war is something that has concerned me for quite some time and provides the necessary satire for this film," said Moore, a vocal critic of George W. Bush's war on terror. The acclaimed filmmaker added that there was no specific trigger that prompted him to make the documentary.
"I have always been a little bothered by that. That's where the comedy comes from," he added.
TIFF organizers described the film as Moore's "most provocative and hilarious." The filmmaker "tells the Pentagon to 'stand down' – he will do the invading for America from now on," they said.