Sienna Miller keeps it simple in a gray tank as she arrives at LAX airport in Los Angeles after jetting in from London on Sunday.

The 26-year-old actress has been promoting her new film The Edge of Love in England the past few days.

Ms. Miller recently shared about her Edge of Love co-star Keira Knightley, saying, “Keira is the most beautiful woman in the world. We totally bonded on the movie and it was so amazing to find a girlfriend in the business!”

25+ pictures of Sienna Miller going gray… More Here! »

Keira Knightly is pretty in purple Erdem at the Private VIP Party for her and Sienna Miller’s new movie, Edge of Love at the Berkley Hotel on Thursday in London, England. (Si’s dressed in Jasmine Di Milo.)

Yesterday at the Edinburgh International Film Festival, Keira expressed how happy she was to go nude on film.

“I always bare my breasts,” she said. “It’s not like it’s only in this film!”

Referring to a scene The Edge of Love with her onscreen husband Cillian Murphy, Keira said: “It was very simple. It was a sex scene and I never like them when they’ve got bras on.”

15+ pictures inside of VIP princess Keira Knightley… More Here! »

Sienna Miller (in Jasmine Di Milo) gets a little crazy on the red carpet with her black bowler hat and fringe dress at the world premiere of her new movie, The Edge of Love on Wednesday at the Edinburgh Film Festival in Scotland. Costars Keira Knightley (in Chanel) and Matthew Rhys were also present.

To check out Keira and Sienna face off as contestants in a barrage of questions about the other’s career, visit EmpireOnline.com. The prize? A strawberry-flavored lollipop! (Spoiler: Keira wins! Hehehehe.)

10+ pictures inside of Sienna Miller on the fringe… More Here! »

Sienna Miller (in Twenty8Twelve) joins costars Matthew Rhys and Keira Knightley (in Topshop) at a photocall for their new movie, The Edge of Love, on Wednesday in Edinburgh, Scotland.

Sienna just confirmed that she’s set to play Maid Marian alongside Russell Crowe’s Sheriff of Nottingham in the new remake of Robin Hood.

“I just found out,” Sienna, 26, tells the BBC. “It’s the most exciting news in the world. It’s ridiculous. But there’s this looming actor’s strike, so it’s not 100% sure that it’s going to be made, but it’s looking pretty certain.”

Crowe will team up with Gladiator director Ridley Scott again for Robin Hood.

40+ pictures inside of Robin Hood star Sienna Miller… More Here! »

Keira Knightley and camera-shy costar Sienna Miller do interviews at Radio One studios in central London on Tuesday.

The pair promoted their latest movie, The Edge of Love. The story is based loosely on real events and people. During World War II, Vera Phillips (Knightley) runs into her first love, charismatic Welsh poet Dylan Thomas (Matthew Rhys), and their feelings for each other are renewed, despite that Dylan is now married to the spirited Caitlin (Miller). Despite their rivalry, the two women become friends and the trio have happy times together. When Vera marries soldier William Killick (Cillian Murphy), Dylan becomes jealous at the addition of him to the group, and Caitlin notices. But William is soon deployed abroad, and the remaining trio moves to the Welsh countryside, and Vera’s feelings for William intensify. When William comes home from the war, his jealousy explodes and he attacks Dylan.

The Edge of Love opens in UK theaters this Friday, June 20. No U.S. release date has been set yet.

Sienna Miller opened up about her love for fellow actor Rhys Ifans in the July issue of UK’s Elle.

Here’s what the 26-year-old G.I Joe actress had to say:

On the mere mention of Rhys’s name making her jump for joy: “When his name is mentioned, it makes me smile like a fool because I instantly think of him and it makes me happy. He does just make me happy. I totally love Rhys.”

On how the couple spend their quality time: “[Rhys] is the best cook ever. His cooking completely reflects his personality; he does these mad, quirky dishes that taste completely wonderful, like carrots poached in mandarin juice.”

On her loads of other food fetishes: “[Caviar;] Chicken and stuffing sandwiches; milk chocolate with salt-and-vinegar [potato chips], in the mouth at the same time – you just have to try it – and French fries dipped in [a] chocolate milkshake.”

On the rumors that she might be engaged: “No ring. It’s so embarrassing when these stories come out and your relationship has been somehow fast-forwarded. We both had our mums on the phone. It’s just awkward. But I’m so happy with our relationship as it is.”

Check out this new photo of Sienna Miller as the bloody Baroness in the new G.I. Joe, which is currently filming in Prague, Czech Republic.

Sienna prepared with four months of weight training, boxing sessions and learned to fire live ammunition, gaining five pounds of muscle. Her character plays partner to Destro (Christopher Eccleston).

Click on over to IESB for more photos. Sienna’s wearing head-to-toe leather, including wedge heels, studded belt , trench coat and sleeved gloves. Hot!

Here are some untagged, high quality promo pictures of the G.I. Joe: The Movie cast.

Pictured below (left to right, top to bottom): Byung-hun Lee as Storm Shadow, Saïd Taghmaoui as Breaker, Channing Tatum as Duke, Sienna Miller as The Baroness, Christopher Eccleston as Destro, Dennis Quaid as General Hawk, Rachel Nichols as Shana ‘Scarlett’ O’Hara, Ray Park as Snake Eyes, Marlon Wayans as Ripcord and Adewale Akinnuoye-Agbaje as Heavy Duty.

G.I. Joe: The Movie storms into theaters on August 7, 2009.