LOS ANGELES (AP) Matt Damon's Jason Bourne seemingly never met a man whose neck he couldn't break.

As the son of an academic specialising in nonviolent conflict resolution and the father of a year-old girl, Damon's selective about the sort of screen violence in which he'll participate, though.

Damon, 36, returns for his third go-round as the amnesiac former assassin in "The Bourne Ultimatum," his character returning to his roots to find out how he became a killing machine so he can finally put that life behind him.

From his mother, a professor of early-childhood development, Damon was indoctrinated from an early age to look for ways to avoid the sort of altercations that are part of daily life for Bourne.

"Every role I took, there's always a special eye toward the violence," Damon said in an interview with The Associated Press. "Violence is part of the human condition. The question is: Are you desensitising people to violence by what you're showing?

"The reason I'm allowed to do this movie and still have a relationship with my mother is because the character bears the responsibility for his actions in a way, and you see the price that he pays for the life that he's chosen to lead."

Damon and his wife had a daughter in June, 2006. Fatherhood has Damon thinking more about doing a children's film, something he could show his daughter, unlike the "Bourne" flicks, which he said "she's not going to see for quite a while".

Becoming a parent also has reinforced the values that have guided Damon over choosing roles in general.

"Those are the kinds of things where I say, 'Well, do I want my daughter exposed, knowing that her dad makes movies like this or that?'" Damon said.

"There are so many movies that drive my mom just totally crazy, because there are these thousands of acts of violence. The movies are rated PG-13, but the toys are marketed to ages four and up. So you get these kids who are just getting pounded by this imagery from a very young age. I don't want to be a part of that."

With his boyish face, Damon did not seem a likely choice to play an action hero when he was cast as Robert Ludlum's memory-challenged terminator in 2002's "The Bourne Identity".

Previously, Damon had done mostly drama, including "All the Pretty Horses", "Saving Private Ryan", "Rounders" and "Good Will Hunting", which won him and buddy Ben Affleck an Academy Award for their screenplay.

Damon did the occasional thoughtful thriller such as "The Rainmaker" and "The Talented Mr. Ripley", and he has been one of the all-star gang on "Ocean's Eleven" and its two sequels. The chance to play Bourne came as a surprise.

"I kind of just react to whatever's out there, and this was definitely the best script that was out there," Damon said of "The Bourne Identity".

"It was this kind of movie that I hadn't really pictured myself being offered but had pictured myself doing, had hoped that I'd be able to do."

With "Bourne Identity" becoming a $100 million hit, Damon's opportunities broadened, particularly after the 2004 follow-up "The Bourne Supremacy" also turned into a smash.

Damon had a plum role in the 2005 ensemble drama "Syriana." Last fall, he starred as a crook who infiltrates the police force in Martin Scorsese's "The Departed" and as one of the masterminds who helped found the CIA in Robert De Niro's "The Good Shepherd."

"The Bourne Ultimatum" was preceded this summer by "Ocean's Thirteen," with Damon teaming again with director Steven Soderbergh and co-stars George Clooney and Brad Pitt for another casino caper.

"This is his time," said Paul Greengrass, who directed "Bourne Supremacy" and "Bourne Ultimatum".

Greengrass said he could not have inherited a better actor to play Jason Bourne.

"He's got a particular skill set as an actor that makes him perfect for this," Greengrass said. "He's a brilliant actor of duality. He's done it on a number of films back from the beginning. 'Ripley's' a classic example. Because he's got that open face, and yet it's capable of dark actions. It makes him very, very morally ambiguous.

"I think he's been at his best on the screen when he's explored that. Particularly so in `Bourne,' because the character itself is a duality, with the dark past and the renounced past."

Co-star Joan Allen, reprising her "Bourne Supremacy" role as a CIA spymaster sympathetic to Bourne, said Damon packs as much conflict into the character as the movie packs action.

"When I look at some of the moments that he has, I can't believe the number of things he has going on simultaneously," Allen said. "Here's a character that has these super powers, he's very smart, he doesn't really understand, he's confused and he's tortured. And sometimes, I see all that in Matt in just a look. ...

"I think he's also very sexy as he does it. Even though there's very little overt sexuality, these are very sexy films, and he is very sexy in them."

Damon said he senses he's done with the "Bourne" films, but he might be interested if Greengrass were to return to make another. Greengrass and Damon hope to collaborate on the Iraq war drama "Imperial Life in the Emerald City", though Damon may be unable because of a scheduling conflict for Soderbergh's upcoming corporate-whistleblower tale "The Informant".

Amid his busy schedule, Damon also hopes to work with Affleck again at some point and follow his friend's lead by directing a movie. Affleck's directing debut, "Gone Baby Gone," is due out this fall.

"I'm jealous that he got to do it first," Damon said.

Ludlum's "Bourne" books were set amid the Cold War, but Damon said the movie adaptations reflect our current world. Though the Iraq war is not explicitly mentioned, Bourne's actions and revelations serve as a commentary on those events, he said.

"I just love that he tries to atone for what he's done at the end of the second movie. It was a really nice thing in a kind of mainstream action movie. To have that be your final beat is something I had never seen before, and I liked what that said particularly at that time," Damon said.

"All of these movies are very much of the time that they were made, and at a time when we had gone into this war. To have this character aware of what he had done and try to take responsibility for his actions I thought was a really good thing."

And how is "Bourne Ultimatum" of its time?

"It's this guy who has done these horrible things, but now we see he thought he was doing them for the right reasons at the time he did them, but he realises he was sold a bill of goods," Damon said. "So that's very much a movie for today."