Not shaving, Private Ryan?

Ryan Phillippe is hanging out of the window of his London hotel room, smoking a cigarette. He wears grey pin-striped trousers and strange white trainers with a fat wedge. A black T-shirt with ripped-off sleeves reveals chunky brown biceps. His wrists are adorned with bracelets made out of elastic and cotton. His hair is a mass of baby ringlets and he’s growing a patchy beard.

I’m not expecting this Hollywood star, who made his name in the late 1990s with I Know What You Did Last Summer and Cruel Intentions, to be friendly, smart, articulate and open. After all, it’s not even a year since his divorce from Reese Witherspoon was announced. Yet here he is, chatting about joint custody, child rearing, hard times and war. Perhaps his choice of recent films should have given something away: after Gosford Park, he co-starred in Crash and Flags of Our Fathers. At almost 33, he is a serious actor.

Phillippe is part of an emerging Hollywood movement that is raising questions about the war in Iraq. At Venice next week Paul Haggis – who won best film Oscar for Crash – will present In the Valley of Elah, a drama inspired by the killing of a soldier home from duty in Iraq. Brian De Palma’s Redacted tells of an army squad persecuting an Iraqi family. John Cusack stars in Grace is Gone, about a father whose wife is killed on duty in Iraq. Paul Greengrass is about to start work on Imperial Life in the Emerald City, about the Green Zone in Baghdad.

And Phillippe himself is the star of Stop Loss, the second feature film by Boys Don’t Cry director Kimberly Peirce, in which a Texan soldier defies the government mandate to return to Iraq. ‘What Stop Loss says about Iraq is similar to what The Deer Hunter said about Vietnam. Kim’s brother signed up after 9/11, and the story is based on his best friend in Iraq. I think it’s probably the best work I’ve ever done,’ says Phillippe.

Is he patriotic? ‘In some ways: both my grandfathers fought in the Second World War and my dad was in the navy during Vietnam. I would have laid down my life to fight the Nazis but I’ve serious misgivings about almost every war in which the US has since been involved. There’s a definite feeling in the US now that the war in Iraq was based on a lie.’

Over the past few years Phillippe has done back-to-back movies, which, he offers obliquely, may have affected his marriage. ‘It was brutal. It contributed to a lot of bad things that happened in my life. I’m going to be working in Europe for the next four months – including a Viking movie with Menno Meyjes, hence the beard – and then I’ll take time off.’

One of the films that may have pushed his relationship over the edge – which is not to say that Witherspoon doesn’t work equally hard, picking up an Oscar last year for Walk the Line and now reputedly commanding $29m per movie – is Breach. It is a fine, gripping thriller based on the true story of the FBI counterintelligence agent Robert Hanssen (the incredible Chris Cooper), who sells secrets to the Russians. Phillippe plays Eric O’Neill, the agent-in-training who exposes him; Hanssen is arrested months before 9/11.

Working with Cooper was ‘like taking a masterclass in acting’. And, says Phillippe, he no longer has to manufacture emotions. ‘When I was young I didn’t have much to be upset about. But I could cry right now, sitting here, just because of what I’ve been through.’ He worries most about his kids, Ava (seven) and Deacon (three). ‘Reese and I live near one another and have joint custody: I can’t imagine not having the level of influence and protection to which I’ve become accustomed.’

He worries about the paparazzi and desperately wants the children to have the regular upbringing he had in Delaware. ‘Reese and I got together on her 21st birthday; I was just 22. At that time you have no concept of the ramifications of bringing two kids into this crazy lifestyle. It takes extra work to counterbalance all the weirdness.’ He fiddles with his bracelets, then smiles. ‘Having kids is the best, man. They take me away from problems. They don’t care that I’m some movie star.’

· Breach is released on Friday