Even if you weren't aware that Aaron Sorkin is the screenwriter of Charlie Wilson's War, you'd recognize the shrewd, snappy patter from the writer's television work. The dialogue here is quick and quirky, sort of a big-screen version of Sorkin's West Wing with some Gilmore Girls thrown in. The talk comes at us in big sparkling bursts, and it all goes a long way toward turning potentially dry or otherwise shaky material into something interesting.

Based on true events from the Reagan years, Mike Nichol's new film stars Tom Hanks as Charlie Wilson, a hard-partying Texas congressman who sets monumental forces in motion, almost without realizing it, when he begins lobbying to supply Afghanistan's Mujahideen in their struggle against Russian invaders. Urging Wilson on is his occasional lover, a rich, ultra-right-wing dragon lady played by Julia Roberts, her already outsized features further exaggerated by make-up and big hair that make her look like an over-the-hill drag queen.

The individual players are fairly engaging, but Charlie Wilson's War never manages to muster up much dramatic momentum. The movie's tone is all over the place, veering from Sorkin's trademark sitcom style to quasi-screwball satire to something approaching sentimental mush, and then straight into agitprop, with tears welling up in Hanks' eyes in the midst of multitudes of mistreated Afghan orphans.

Charlie Wilson's War starts out strong and then slowly fizzles out just as it should be getting interesting. The covert war waged by Hanks' congressman results in the Soviet empire crumbling just as the film is ending, all but ignoring the more interesting twists that followed (specifically, how Afghan "freedom fighters" transformed into the legions of Osama bin Laden and the Taliban, using American weapons and training against their so-called benefactors). The movie opens with a dreamily stylized image of a Muslim praying beneath a starry sky, then picking up his rocket launcher and aiming at squarely at the camera — which is to say, at us – but that's about as close as — Nichols gets to that particular can of worms.

Charlie Wilson's War (R) Stars Tom Hanks, Philip Seymour Hoffman, Julia Roberts and Amy Adams. Opens Dec. 21 at local theaters. 1/2 —Lance Goldenberg