To call documentarian Alex Gibney prolific would be something of an understatement, as a director who works on several projects at any given time. The latest to secure distribution is Zero Days, an unnerving, investigative piece into cyber weapons, and in particular, the malicious computer worm Stuxnet.

We spoke to Gibney at the Berlin film festival – where this film was screened in competition – about the level of secrecy attached to Stuxnet, and his run-ins with the NSA. He also explains how he had to change direction during the making of the film, following on somewhat from the last time we spoke to him, for The Armstrong Lie.

You often make politically inclined documentaries, but do you think you’ve ever made one quite as investigative as Zero Days?

I’ve done a number of films that have been investigative, but I’ve never done one about something that has been so resolutely kept secret. That was the big problem. The film ended up being partially about that, in a way that I didn’t expect when I started. Sure, I knew the NSA are known for its secrecy, but I started with the Stuxnet story and something about it was already known, I didn’t expect to be in a situation where I would ask people about something that clearly already happened and people would refuse to comment that was evident to everybody. It seemed like the Stuxnet story itself was a kind of origin moment and worth telling on its own, I didn’t know it was going to take me to a much bigger terrain, there was a much bigger story there than I initially thought.

People were quite afraid of speaking to you, did you ever have any apprehensions in releasing all of this information, and investigating it yourself?

I have enough experience in doing these kinds of things to feel that I could go there. So I was cautious, and we intentionally kept this film under wraps for a long time, I didn’t talk about it really at all. I got an email today from the NSA which I found amusing, because we’ve been pestering them for years to let us inside like they did with 60 Minutes after the Snowden revelations, but they were always imposing ridiculous conditions.

Such as?

Well they wanted editorial control, and that was not a condition I was willing to accept. Anyway, today they emailed to get back to me about that interview request [laughs].

This is obviously an amazing expose, but what do you consider to be the major breakthrough here?

There’s two things. One is Nitro Zeus, an operation that was not previously disclosed. It’s significant because it tells us that the NSA has gone beyond Stuxnet in terms of the size and complexity of its cyber weapons. The other thing that is interesting, is to understand how the Stuxnet worm got loose, and that had to do with the fact that, pressured by Netanyahu, Meir Dagan changed the code in ways that was extremely aggressive, so that it spread all over the world. That is both interesting from a technical standpoint, to understand how the weapon works, but also tells us a lot about the US/Israeli relationship. The US clearly did not want that to happen.

There’s a lot of conversations about coding, and it gets quite deep into that side of things. How did you go about ensuring this would remain accessible?

Well the key was me. I’m a nitwit when it comes to this stuff, so I felt if I could understand it, anybody could. Nevertheless I had on my team those who understood this world technically very well, we had a copy of the Stuxnet code in our office. If this was a detective story, I’d be the most bumbling, the Colombo, and the other detectives were the Symantec guys, and they followed the code, and the other detectives were the political guys, the journalists, who were following the politics. So I felt if this was an action thriller with a detective vibe, that is what would allow the viewer to follow it.

Zero DaysWhat would you ask the NSA now, if they did grant you that interview?

I doubt very much they’d grant me that interview, unless they change completely as an institution. There are still a lot of questions I have about the Stuxnet worm itself. Who invented it? We still don’t know whether it was the Americans or the Israelis. How did the cooperation work? I’m also interested to know, and this is something they certainly wouldn’t tell me, but if I had the power to force them to answer my questions, if I could water board them, then I would ask them how many more weapons like Nitro Zeus do they have.

I left the cinema terrified, mostly because there are a lot of idiots out there in control, and human error is prevalent.

That is mostly what scares me. I’m not a conspiracy theorist, I believe more in the idiot theory, particularly when you have very smart machines coupled with reckless and careless people, there’s a problem. In fact I should tell you that people who spoke up, who had worked at NSA, spoke up precisely because they felt that a number of their superiors really didn’t have a sufficient grasp of how dangerous these weapons were.

Is there any legal framework being drawn up for this?

No, as far as I’m aware there’s not even a conference being held at a high level between nations to try and figure out what kind of legal framework there should be. In part because nobody wants to admit. The US have still not admitted publicly that they have ever used a cyber weapon.

You mentioned earlier that the documentary turned on its head, and became about the fact you weren’t getting information – is that something that occurs during the process, while doing the interviews you think about changing the angle – or is it established more so in post production, like with The Armstrong Lie?

I’ve learned over time, and with some sense of confidence, and the fact these films usually take some time to do, it’s why I often work on more than once, that over time things change. When you get blocked you head in a different direction, or you learn something you didn’t expect and you follow that trail. That’s one of great things about documentaries, you write the script at the end and not the beginning, but along the way you have to be willing to be flexible to change your mind about stuff, and that’s certainly what happened here.

But you must’ve got disheartened when you got blocked? Or does it make you more determined?

When I first started out in documentaries, I was much more mentally rigid about figuring out at the beginning what I wanted to say, and also in the cut, when I couldn’t get the results I wanted, I felt very frustrated and would get really agitated. Over time I’ve learnt that the way is blocked, but I will find a way.

Have you ever had to give up on a project?

Once I’ve actually started a project, I’ve never given up. One lesson I learnt early on when I was a student, was after I saw a wonderful film called Waiting for Fidel. It was a whole movie about meeting Fidel Castro, and they never got to meet Fidel Castro, but it made for a much better movie.

Zero Days is released on January 6th, and you can read our review here.