Tim Hetherington can still recall the evening last summer when, after a screening of his latest documentary Restrepo in a Texan city, an elderly man in the audience approached him. Saying how impressed he was with the documentary - which revolves around an American platoon's deployment in one of the most perilous parts of Afghanistan in 2007 and 2008 - the man handed Hetherington a gift: his Vietnam service medal.
'I said I can't possibly accept that,' says the British photographer-filmmaker in a phone call from New York, where he now lives. 'But he said, 'No, I really want you to have it, because I want to thank you for telling our story'. That suddenly I realised we were not telling a story about Afghanistan - we were telling a timeless story of what soldiers go through. It was appealing not just to those who have served in Afghanistan or Iraq, but those who have fought in all sorts of wars.'
Restrepo is unlike most documentaries made in the past decade about the US army's campaigns in Afghanistan and Iraq, as it provides no background information or talking-head political analysis of the wars. Instead, the film never strays from the 15 soldiers stationed in an isolated outpost in the Korangal Valley, an area in northeastern Afghanistan. The film is mostly made up of the footage Hetherington and co-director (and journalist) Sebastian Junger shot during the six months they spent with the platoon.
'The film isn't necessarily about Afghanistan or about the war - saying that the Korangal Valley is representative of Afghanistan would be like saying Hong Kong is representative of China, or Detroit is representative of America,' says Hetherington.
'It's not. It's just a particular place and a particular experience, What we're interested in is to take you as close as you can to the experience of a soldier.'
And an unnerving experience it is, too. While there are relatively calm moments in the film - such as the soldiers wrestling with each other during their downtime, or conducting 'hearts-and-minds' operations with local chiefs (who explicitly rebuff the soldiers' overtures by questioning the surging civilian casualties) - Restrepo also contains hair-raising scenes in which the filmmakers capture the troops in combat, with bullets and bombs whizzing over their heads.
When the pair arrived in the outpost (named Restrepo after the platoon medic who died before their deployment to the valley) the soldiers were 'still building it - there was no running water, electricity, hot food, showers, internet or phones', says Hetherington.
'We were on a 15-, 20-man outpost on the side of a mountain that was attacked almost daily. And we did everything the soldiers did - we slept like they did, made their food and went on patrol with them on every combat situation.
'After a couple of trips, the soldiers realised we were going to go the whole way with them, that we would do anything necessary ... to stay with them, their trust opened.'
While critically acclaimed - it won the Grand Jury Prize at the Sundance Film Festival in January - the film has also attracted criticism from detractors who question the filmmakers' decision not to tackle the geopolitics which gave rise to the military conflicts. Hetherington agrees Restrepo offers a 'paradigm shift', but dismisses views that war documentaries should make a stand on wars.
'When you're making a work about war, especially an ongoing war, the left-wing or far-left seems to think you're a coward [if you don't] morally condemn the war. And the far-right seems to think that if you are questioning the basis or the rationale of the war, somehow you're unpatriotic. Sebastian and I think these two extreme points of view are not really useful to a discussion of the war and what is happening,' the filmmaker says.
Hetherington says this 'emotional context' of the war is crucial given that recent figures show eight US army veterans commit suicide every day. 'They are not being understood,' he says. 'The political framework is not doing them any good at all.'
Restrepo: Outpost Afghanistan, an edited version of the film, is screened on Saturday at 11pm on the National Geographic Channel