Based on the true story of Chris Kyle, director Clint Eastwood’s “American Sniper” brings us the life experiences of the most lethal sniper in American military history — whose exploits in the war in Iraq led him to be nicknamed “Legend.” Sienna Miller portrays Taya Kyle, the wife of the famous U.S. Navy SEAL sniper, who was killed in February 2013 by a troubled fellow war veteran shortly before “American Sniper” went into production.

During a recent Chicago visit, Miller talked a lot about the impact of war on both soldiers and their families and how making this movie changed her perception of the international conflicts that have always been with us.

“It’s a very polarizing film,” Miller admitted. “But it’s an important, thought-provoking one for sure. It made me think about war in a way that I never really had done before. It was always something I read about but kept at arm’s length. You forget that while we should be so grateful to people who are in active service, we also need to remember the people who are sacrificing their loved ones — to go and do this for the protection of others.

“It’s a really challenging position to be in. I have huge, newfound respect for everybody involved. It’s so difficult.”

Sienna Miller joins director Clint Eastwood and co-star Bradley Cooper at the premiere of "American Sniper." | Theo Wargo/Getty Images

Sienna Miller joins director Clint Eastwood and co-star Bradley Cooper at the premiere of “American Sniper.” | Theo Wargo/Getty Images

Clearly a positive experience for Miller was getting to meet the real Taya Kyle. Bradley Cooper, who plays Chris Kyle, sadly only got to talk to the former soldier on the phone before he was killed.

“I came on board the project about three months before we began filming. We originally met via Skype, and then when I got to L.A., we hung out there. She’s incredible. She’s obviously now a very different woman from the woman she was when I was playing her, because she’s gone through this unspeakable tragedy. But she still has got this gregarious, charming, outgoing and completely open personality. She’s tough. She’s resilient. I completely just loved her as a woman.”

I asked the actress how she went about absorbing things about Taya that she felt would help in a realistic portrayal.

“Initially,” she said, “it started with studying mannerisms and dialect and those kinds of technicalities, which you then hope you’ll forget about once you’ve mastered them.”

Beyond that, Miller wanted to have Kyle share stories from her life that were to be depicted in “American Sniper” — asking if the script reflected actual details of real events.

“I was particularly interested in the scenes on how they met. Taya told me that indeed they did meet in a bar, proceeded to get very drunk, and that she did throw up. That did happen.

She told me she was in a horrible mood that day and when she went to the bar, she really didn’t want to talk to anyone. I love the introduction to her as a character in the film, because it first seems she’s got a bad attitude, and I think it’s a really brave way of introducing someone who actually will turn out to be a great person.

“The fact that she’s so disarmed by this man — and does a 180-degree switch in that scene — is really an interesting way for the audience to meet someone in a film. As an actress, it was wonderful to play.”

Kyle told Miller the biggest burden she bore while her husband was on his multiple tours of duty in Iraq was “about being married to someone you loved so deeply but not knowing whether they would survive. That was a concern she had every day.

“Plus, she was left behind to raise the children on her own.”

As Miller learned, Taya Kyle was very aware of her husband’s life priorities. “Chris’ priorities were God, country, family, in that order. I was interested in knowing from Taya how she felt coming in third,” Miller said. “She accepted it because of the deep love they shared.”

Miller laughed when I told her she was virtually unrecognizable in her two film roles this year (“Foxcatcher” as well as “American Sniper”) — because of how she performed and not due to any extensive hair or makeup changes.

“That’s great. Thank you. Of course, that’s kind of your job, isn’t it? … My own dad watched [‘American Sniper’] the other day, and he didn’t realize it was his own daughter at first in the first scene I appear in the movie. I took that as a huge compliment!”