Robert Downey Jr. appeared in great spirits in a series of fun social media snaps with his Oppenheimer co-stars in New York City on Sunday.

The actor, 58, was surrounded by Emily Blunt, Cillian Murph and Matt Damon as they enjoyed a break from their press tour.

The group snaps were taken in front of the stunning NYC skyline while Emily’s husband John Krasinski made an unexpected appearance.

He captioned the Instagram post: ‘Linking up with my Oppenheimer cast mates…wait, is that a Krasinski photo bomb or might there be a surprise cameo???’

Christopher Nolan has claimed that early viewers of Oppenheimer have left the film ‘devastated’ and ‘unable to speak’.

Happy: Robert Downey Jr. appeared in great spirits in a series of fun social media snaps with his Oppenheimer co-stars in New York City on Sunday (Emily Blunt, Robert, John Krasinski, Cillian Murph and Matt Damon pictured L-R)

The upcoming historical thriller centres on the life of American theoretical physicist J. Robert Oppenheimer, who was director of the Los Alamos Laboratory responsible for the creation of the first atomic bomb in the Manhattan Project.

With its anticipated release scheduled for July 21, the British-American director, 52, has now commented on how early viewers have received the film.

Speaking to Wired magazine , he explained: ‘Some people leave the movie absolutely devastated. They can’t speak.

‘I mean, there’s an element of fear that’s there in the history and there in the underpinnings. But the love of the characters, the love of the relationships, is as strong as I’ve ever done.’

The film stars some of the most famous faces in Hollywood, including Peaky Blinders ‘ Cillian Murphy, 46, as J. Robert Oppenheimer and Emily Blunt , 40, as his wife, biologist and botanist Katherine ‘Kitty’ Oppenheimer.

Little Women star Florence Pugh , 27, plays psychiatrist Jean Tatlock – while Matt Damon portrays General Leslie Groves Jr, director of the Manhattan Project.

Nolan said: ‘It is an intense experience because it’s an intense story. I showed it to a filmmaker recently who said it’s kind of a horror movie. I don’t disagree.’

The director even admitted he was ‘relieved to be finished’ with the project due to the emotional toll it took.

‘As I started to finish the film, I started to feel this colour that’s not in my other films, just darkness. It’s there. The film fights against that,’ he said.

Written and directed by Nolan, epic thriller Oppenheimer thrusts audiences into the pulse-pounding paradox of the enigmatic man who must risk destroying the world in order to save it.

Pals: The actor, 58, was surrounded by Emily Blunt, Cillian Murph and Matt Damon as they enjoyed a break from their press tour

Nail-biting: With its anticipated release scheduled for July 21, the British-American director, 52, has now commented on how early viewers have received the film

The film centres on the life of American theoretical physicist J. Robert Oppenheimer, responsible for the creation of the first atomic bomb in the Manhattan Project.

In August 1945 the bombs were detonated on the Japanese cities of Hiroshima and Nagasaki – the only use of nuclear weapons in war to date – to end the Second World War.

It is based on the Pulitzer Prize-winning book American Prometheus: The Triumph and Tragedy of J. Robert Oppenheimer by Kai Bird and the late Martin J. Sherwin.

The three-minute long new trailer is tense, showing the race against time to develop the bomb and the moral dilemmas that come alongside it.

Other famous faces include Robert Downey, Jr who plays Lewis Strauss, a founding commissioner of the US Atomic Energy Commission.

Benny Safdie plays theoretical physicist Edward Teller, Michael Angarano plays Robert Serber and Josh Hartnett plays pioneering American nuclear scientist Ernest Lawrence.

Oppenheimer also stars Rami Malek and reunites Nolan with eight-time Oscar nominated actor, writer and filmmaker Kenneth Branagh.

It comes after Cillian Murphy said he was ‘desperate’ to land lead role in Christopher Nolan’s upcoming Oppenheimer after five films as a supporting actor.

‘I have always said publicly and privately, to Chris, that if I’m available and you want me to be in a movie, I’m there,’ he said.

‘I don’t really care about the size of the part,’ Murphy revealed in an interview with AP. ‘But deep down, secretly, I was desperate to play a lead for him.’

It turns out Murphy didn’t have a clue about getting the lead role in Oppenheimer until Nolan called him up out of the blue and offered him the part.

Coming soon: The IMAX-shot film Oppenheimer is set to hit cinemas from July 21

‘He’s so understated and self-deprecating and, in his very English manner, just said, “Listen, I’ve written this script, it’s about Oppenheimer. I’d like you to be my Oppenheimer,”‘ Murphy recalled, before adding, ‘It was a great day.’

The actor decided to focus his pre-shoot preps on learning more about J. Robert Oppenheimer and what inventing the atomic bomb does to the individual, the actor told The Guardian last year.

‘You realise this is a huge responsibility. He was complicated and contradictory and so iconic,’ Murphy said of Oppenheimer the man, adding, ‘But you know you’re with one of the great directors of all time.

‘I felt confident going into it with Chris. He’s had a profound impact on my life, creatively and professionally. He’s offered me very interesting roles and I’ve found all of them really challenging. And I just love being on his sets.’