Political satire In The Loop, a spin-off of award-winning BBC comedy The Thick Of It, is released to UK cinemas on Friday.
Writer-director Armando Iannucci spoke to the BBC about the film's gestation and working with a US cast.
Iannucci was behind the camera on Alan Partridge and The Day Today
Why did you decide to make a movie rather than more episodes of the TV series?
Well, there's going to be another series of The Thick Of It later in the year, if we get it all written.
But I've always wanted to make a comedy film, ever since I went to see things like Annie Hall and Manhattan and Airplane and Spinal Tap. I like the idea of lots of people in a room chuckling loudly at a big screen.
Why have you never made a film before?
Actually, I was attached to a film about seven years ago. I wanted then unknown actors like David Walliams and Bill Nighy in it, and the financiers said, "Argh, we've never heard of these people". It all got a bit fraught and I left.
Could it still be made?
I don't know. The budget would be twice, three times as much now if you wanted David Walliams.
How much do you subscribe to the idea that politicians don't have a clue?
I don't think that politicians are bad and evil. I think they're just human and, like anyone, they are fallible. Behind those big grand edifices, like the Washington State Departments and the Pentagon, they're just like us.
You know, we get into work and we do stuff and we think, "Oh no! I got that wrong, I hope nobody finds out. What shall I do? I'll just pretend it never happened!"
And that's what happened, apparently, when Bush was planning the invasion of Iraq. If somebody said, "What happens after we invade?" everyone would just look at the floor. Like kids not wanting the teacher to catch their gaze because they don't have the answer.
Does that frighten you?
Yes, it scares me senseless and I think it ought to be shown on the screen.
The film has been described as an X-rated Yes, Prime Minister. Do you think that's fair?
You could say that. There's no explicit sex or anything.
One thing I ought to say, though, is that you needn't have seen or indeed heard of The Thick Of It to get In The Loop. We wrote it in such a way that its new characters and it has its own start-to-finish storyline, so you don't need to have any background knowledge.
One character who does return is Malcolm Tucker - Peter Capaldi's character - who really has turned swearing into a new art form.
I remember getting a letter from an 84-year-old lady, and I thought, "Oh dear, this is going to be a complaint". But she said she found Malcolm's language positively Shakespearean. Which I take as a compliment!
If it was just swearing, it would be boring, so we come up with more and more elaborate and intricate ways to allow the swearing to happen. It's a combination of swearing and threats - and if we make the threats more elaborate and physical then it sort of justifies the swearing.
Peter Capaldi plays the profanely aggressive Malcolm Tucker
Do you realise that people are quoting it now?
Yes, and I have to apologise for that. I'm sorry that licence-payers' money has been spent on that.
I'm not saying that I'll return that money. The amount of money spent by the licence-payer on propagating swearing I think is incalculable and so cannot be returned.
The main difference between the TV programme and the film is the addition of the Americans. How much fun was Washington?
Initially it was frightening, because I had no idea if it was going to work. I spent a long time in Washington doing research and then, with the casting, finding people who I knew I could work with, who had a comic brain, and were happy to improvise along with the UK cast.
We rehearsed in an enormous hotel in New York that had 100 floors, and it was just an enormous space-age kind of hangar really. And we had that room for a week, and all the American cast came, and some of the UK cast came over, and we workshopped it and that was really fun, to see the two casts gel.
You have James Gandolfini as the sort of Colin Powell character.
He's a Pentagon General who talks the talk, but can he walk the walk? And I liked that idea of using James, because I wanted someone who had charisma - and who the Brits in the film would actually be slightly in awe of - but who is increasingly vulnerable and a little bit rubbish.
How was he to work with?
James was a fan of The Thick Of It - and happily got stuck into all the rehearsals and the improvisations.
He even went off to the Pentagon! He rang them up and said, "Can I come round for two days?" And, of course, they said yes. He took generals out to lunch and asked them if they'd ever killed anybody. And he went to the Pentagon barber so he could have a genuine General's haircut.
Is it true that he brought his basketball to the set?
Yes, we were filming in this sports centre in London that we'd built the State Department in, and one day he just got his basketball out and said "do you want a game?"
And all these people, who are the most unsporty people ever, comedy writers are not into rock'n'roll and football - suddenly they all knew everything about basketball, singing the Harlem Globetrotters theme tune and everything.
Did you play?
No, of course not. And the great thing about being a grown-up is you can say to people, "No, I'm not going to play" and there's nothing anyone can do to make you.
The film had a premiere at the Glasgow film festival in Feb, with your mother in the front row. What was the review?
She loved it. She knew what to expect because of The Thick Of It, so she was forewarned in terms of the language. And she loved it. I thought she'd be knackered - but she stayed well past midnight for the party.
What did you think when Alastair Campbell called the film boring?
I worry that he found it boring because he'd seen it all before, and that upsets me.
Were you tempted to put his quote on the poster?
Well, some people might not know who Alastair Campbell is and they'd just see a poster with the word "boring" on it. I'd rather put all the other good reviews on it.
Have you got the taste for movies now? Will there ever be an Alan Partridge movie?
You must never say yes and never say no about these things.
I want to do more films. The thing I want to do next is a slapstick movie. I want to do slightly more expansive films that look at several storylines. I really love Robert Altman films where you get really good characters and interesting stories and start weaving them all together. But principally I want to do funny films.
Armando Iannucci was talking to BBC Five Live entertainment reporter Colin Paterson.