Kevin Costner Calls Studio Support of Horizon: An American Saga 'Pretty Gratifying' (Exclusive)

Kevin Costner is expressing gratitude for the support he's received over his latest movie.

The Academy Award winner, 69, stepped out for the premiere of his new epic film Horizon: An American Saga in Los Angeles on Monday, June 24.

While there, he exclusively tells PEOPLE how much this night means to him.

"You think a night like this has the possibility of happening, but for a studio to line up behind it to create this environment for us, to celebrate this movie that we worked so hard for and that we dreamed about for so long, is pretty gratifying," he says, referring to distributor Warner Bros.

The director also tells PEOPLE that his children "are watching over" him at the event, noting "they always do."

Costner shares three adult children — Annie, 40, Lily, 37, and Joe, 36 — with his ex-wife Cindy Silva, as well as son Liam, 26, with former partner Bridget Rooney. He also shares Cayden Wyatt, 17, Hayes Logan, 15, and Grace Avery, 14, with now-ex-wife Christine Baumgartner.

He explains to PEOPLE that his children have only seen one cut of the film. "I brought them with me to France, but they're anxious to see it with no subtitles," he adds through a bit of laughter.

Horizon premiered at the 2024 Cannes Film Festival on May 19, with five of his seven children in attendance. He was joined by daughters Annie, Lily and Grace, and sons Hayes and Cayden.

Horizon "explores the lure of the Old West and how it was won — and lost — through the blood, sweat and tears of many," reads the film's synopsis.

"Spanning the four years of the Civil War, from 1861 to 1865, Kevin Costner’s ambitious cinematic adventure will take audiences on an emotional journey across a country at war with itself, experienced through the lens of families, friends and foes all attempting to discover what it truly means to be the United States of America."

In addition to starring in the film, Costner also served as a writer, director and producer of the Western epic, with a sequel titled Chapter 2 releasing Aug. 16. Costner previously told Entertainment Weekly he started working on this film in 1988 and even named his son after the main character he plays — Hayes Ellison. 

“Horizon is incredibly meaningful to me. It's really been the hardest thing I've ever done, but it's exactly what I want to do," Costner told PEOPLE in 2022. "I wrapped this first one, and it took everything I had, but I'm holding on to the rope and not letting go. In my career, I've tried to choose not based on what was popular. I made the films I wanted to make."

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The film features a star-studded cast including Sienna Miller, Sam Worthington, Luke Wilson, Ella Hunt, Isabelle Fuhrman, Jamie Campbell Bower, Jena Malone, Owen Crow Shoe, Tatanka Means, Wasé Chief and Michael Rooker.

Costner told PEOPLE in November 2022 that his 15-year-old son Hayes also makes an appearance in the movie. 

"I kind of did it on purpose, so he could be hanging out with me," the Yellowstone star told PEOPLE. "And the same thing for Cayden, same thing for Grace. I'm like any other parent, I'm trying to figure out, like, 'This is really neat. You should come be with me.'"

Costner is no stranger to the Western genre and said he has always been fascinated by it. His directorial debut Dances with Wolves — a Western adventure film — won Best Picture and Best Director at the Oscars in 1990. 

“A lot of times we measure ourselves against other generations," he told PEOPLE. "I think about what was at stake. How did people survive? There's a rawness and an unpredictability about it. I'm haunted by that.”

Horizon: An American Saga Chapter 1 is in theaters June 28, followed by Chapter 2 on Aug. 16.