Twenty years after Rambo's last bloodthirsty tour of duty, Sylvester Stallone's iconic warrior stumbles out of retirement to wreak havoc on the oppressive Burmese military. In his role as director, co-writer and leading man, Stallone's intentions are noble, refocusing the spotlight on the long-running civil war between ruling forces and the Karen People of Burma, who have been tortured and murdered for nearly 60 years.

But grafting a violent action-thriller on to real-life genocide leaves a nasty taste in the mouth. The underlying message couldn't be clearer: if you want a resolution to the conflict, send in America and let Uncle Sam blow the country to smithereens. "When you're pushed, killing's as easy as breathing," proclaims the big man. If that's true then Stallone should be hyperventilating by the end credits because the body count mushrooms into triple figures in no time at all.

Former Green Beret John Rambo (Stallone) lives and works on the Salween River, close to the Thailand-Burma border, supplying cobras and pythons to a snake village. Missionaries Michael (Paul Schulze) and Sarah (Julie Benz) approach Rambo to take them up river to Burma, where they hope to nurse the sick back to health.

Sarah pricks Rambo's conscience and he ferries them to a remote Karen village. Unfortunately, the community comes under attack from the Burmese military and the missionaries are taken hostage. When pastor Arthur Marsh (Ken Howard) hires a band of mercenaries (Graham McTavish, Matthew Marsden, Tom Kang, Ray Gallegos, Jake La Botz) to extract his people from their tropical prison, Rambo tags along with his trusty bow and arrow.

Rambo is an orgy of senseless carnage, asserting that revenge is a dish best served with an assault rifle. Stallone and co-writer Art Monterastelli paint the Burmese military as two-dimensional monsters, who get their kicks by goading Karen prisoners into running over landmines. To seal the deal, the military leader is also a paedophile. Character development is left down river while Stallone and his co-stars gallop around the jungle, losing limbs and/or their faith in a hail of bullets.

Time has not been kind to the brawny star. He looks his age - 61 and counting; so much so, you have to wonder if Rambo will be able to navigate the perilous jungle terrain without the aid of a Zimmer. Soon, though, Stallone is racing through the undergrowth, making mincemeat of young and sinewy co-stars. Action sequences are breathlessly orchestrated but wanton destruction on such a massive scale is exhausting.