Harry Guerin finds that Clint Eastwood's latest outing as a director leaves its mark. 

Form, as they say, is temporary, class is permanent. After Hereafter, J Edgar and Jersey Boys, there was the feeling in some quarters that Clint Eastwood's powers as a director were in decline and that the chances of him making a must-see film were diminishing with each release. Not a bit of it. This troubling true story of war, male identity and patriotism deserves your custom, and is powered by a pent-up Bradley Cooper whose work here is right up there with Silver Linings Playbook and American Hustle.

Cooper portrays Chris Kyle, a hot-headed rodeo rider whose love of his country and desire to protect it made him enlist in the US Armed Forces. Kyle joined the elite Navy SEALs and at the age of 30 - ancient by SEAL standards - came through the merciless basic training and showed the seen-it-all instructors just what he had to offer: a frightening gift for marksmanship. First deployed to Iraq in 2003, Kyle was to return for three further tours of duty. During his years of service he had 160 confirmed kills, earning the nicknames 'Legend' and 'The Devil of Ramadi'. Behind the ice-in-the-veins icon, however, was the husband and father who struggled to make sense of his world on each return home.

The Samuel Johnson quote, "Every man thinks meanly of himself for not having been a soldier" comes to mind more than once while watching American Sniper, as does that saying about war either turning someone into a madman or a monk. Once again, Eastwood returns to the myth-versus-reality theme that he has explored throughout his directorial career, with Cooper's Kyle the gunfighter who lives by the minute during combat, knowing that the demons await him once the shooting stops. 

Over four tours of duty, we see him become consumed by his quarry and the adrenaline rush, but guilt-ridden by his inability to save and protect even more of his comrades from the rooftops. The combat sequences are brilliantly realised and painfully tense, with Cooper's performance becoming more powerful as the years, and kills, rack up. At home, Sienna Miller plays the wife who sees the man she married missing in action during his visits back to Texas. One of the film's two disappointments is that we don't see more of her.

The other is the ending, which rushes the aftermath of Kyle's service and his final return home. It's a decision that denies viewers the opportunity to see even more of the human cost and to further question their own feelings, whatever they may be, while watching.

That said, you will leave the cinema wanting to know more about Kyle, probably unchanged in your beliefs but definitely wiser than before you sat down. Eastwood, Cooper, Miller and their colleagues have given their audience plenty to talk and think about - it behoves us all to find the time.