Originally Published: 13 JUL 23 15:49 ET

Updated: 13 JUL 23 16:01 ET

By Alli Rosenbloom, CNN

(CNN) — The cast of director Christopher Nolan’s hotly anticipated war-era drama “Oppenheimer” is standing united in the effort to support the SAG-AFTRA strike.

Stars of the film appeared on the red carpet of the film’s UK premiere on Thursday before the strike was officially announced, but they ended up walking out of the event “to write their picket signs,” according to Nolan.

Addressing the audience inside the Odeon Luxe Leicester Square theater before the screening began, as seen in videos posted to social media, Nolan acknowledged the work of Cillian Murphy, Emily Blunt, Matt Damon, Florence Pugh and Robert Downey Jr., among other “Oppenheimer” cast members.

“We have to acknowledge (that) you’ve seen them here earlier on the red carpet,” Nolan said, adding “unfortunately they’re off to write their picket signs for what we believe to be an imminent strike by SAG.”

Nolan continued that the actors who left the “Oppenheimer” premiere in support of the union that represents them join “one of my guilds, the Writer’s Guild, in the struggle for fair wages for working members of the union, and we support them.”

The Writers Guild of America (WGA) has been on strike since May.

Blunt told Deadline on the “Oppenheimer” red carpet Thursday, prior to the cast walking out of the screening and prior to the strike’s official commencement, that her hopes were that “everyone makes a fair deal and we are here to celebrate this movie.”

“And if they call (the strike), we’ll be leaving together as a cast in unity with everyone,” Blunt said, adding, “We are gonna have to. So we will see what happens. Right now it’s the joy to be together.”

The Screen Actors Guild-American Federation of Television and Radio Artists (SAG-AFTRA)’s president Fran Drescher announced in an impassioned speech during a press conference in Los Angeles on Thursday that the union will go on strike.

The strike is set to go into effect at midnight PT Thursday night.

“Oppenheimer” is scheduled to premiere in theaters on July 21.