Robert Downey Jr. is excited about his new film, Oppenheimer.

At the London premiere he even made a claim that might make fans of his Iron Man movies angry.

‘Just going to flat out say it: This is the best film I’ve ever been in,’ he said in a video Deadline posted to Twitter. ‘I cannot wait for you all to experience it.’

He plays Lewis Strauss in the Christopher Nolan film. Strauss is the antagonist of J. Robert Oppenheimer.

‘No matter what your expectations are’ about the film that tells the story of the development of the atomic bomb during World War II, it ‘transcends that,’ he said.

Excited: Robert Downey Jr. is excited about his new film, Oppenheimer

‘This is what a summer blockbuster, when I was growing up, used to be,’ he continued. ‘It just kind of, like, changed your life. But again, you know, it’s why Chris Nolan is who he is.’

And critics agree, with film critic Robbie Collin from The Telegraph raving on Twitter: ‘Am torn between being all coy and mysterious about Oppenheimer and just coming out and saying it’s a total knockout that split my brain open like a twitchy plutonium nucleus and left me sobbing through the end credits like I can’t even remember what else.’

Vulture movie critic Bilge Ebiri gushed: ‘OPPENHEIMER is…incredible. The word that keeps coming to mind is “fearsome.”‘

‘A relentlessly paced, insanely detailed, intricate historical drama that builds and builds and builds until Nolan brings the hammer down in the most astonishing, shattering way.’

Jonathan Dean of The Sunday Times called the film ‘audacious’ and ‘inventive.’

‘Totally absorbed in OPPENHEIMER, a dense, talkie, tense film partly about the bomb, mostly about how doomed we are. Happy summer! Murphy is good, but the support essential: Damon, Downey Jr & [Alden] Ehrenreich even bring gags. An audacious, inventive, complex film to rattle its audience,’ he posted on Twitter.

The London premiere of the film saw the cast, including Matt Damon, Emily Blunt, Cillian Murphy, Rami Malek and Florence Pugh, leaving the red carpet when the news of the SAG-AFTRA strike broke.

The actors left the event prematurely to ‘go and write their picket signs’ in preparation for the ‘strike by the actors’ union,’ according to Nolan.

The reasons for the strike include issues such as the use of unregulated AI as well as the rise of streaming services and how little actors are paid for those shows and movies.

Best film: ‘Just going to flat out say it: This is the best film I’ve ever been in,’ he said in video Deadline posted to Twitter

Can’t wait: ‘No matter what your expectations are’ about the film that tells the story of the development of the atomic bomb during World War II, it ‘transcends that,’ he said

In a red-carpet interview with Variety on the night of the London premiere, Damon said ‘once the strike is officially called,’ the cast is ‘going to walk obviously in solidarity.’

‘That’s why we moved this [red carpet] up because we know the second it’s called, we’re going home,’ he said.

Speaking to Deadline on the red carpet earlier, Emily said: ‘I hope everyone makes a fair deal and we are here to celebrate this movie.

‘And if they call [a strike], we’ll be leaving together as cast in unity with everyone. We are gonna have to. We will see what happens. Right now it’s the joy to be together.’