“Zero Days” is an extremely thorough documentary about Stuxnet, a joint plan by the U.S. and Israeli governments to derail (or at least delay) the Iranian nuclear program through the use of malware. The film tells that story and explores its implications, noting that the successful utilization of computer viruses to create occurrences in the physical world — to cause things to blow up, for example — marks a new chapter in the history of warfare.

But the film’s thoroughness is a virtue or a problem, depending on one’s point of view. For those not particularly interested in the specifics of how computers work, the involved explanation by computer experts into the mechanisms of Stuxnet will be something of a slog. Much more interesting is the glimpse it gives us into the covert side of international relations.

Some of the information is distressing. The notion that we are on the threshold of a new kind of war, one that will inevitably be waged against civilian populations, is unsettling at the least. There is something to fear in enemies getting power over the power grid and shutting down essential services. Nor is it particularly encouraging to hear that the Israelis, in their zeal, ended up blowing the cover on Stuxnet, which seemed like a useful and successful weapon, at least in the short term.

However, it is rather heartening to realize that the United States has a lot of highly intelligent people working in this area. The various operators can’t say much on the record here — the U.S. has never fully confirmed that the Stuxnet operation even happened — but to the extent that they do talk, they seem like responsible, thoughtful people.

Michael Hayden stands out, in particular, as the Shelby Foote of this documentary. A former CIA head and the director of the National Security Agency, he has an impish sparkle even as he’s stonewalling. And when he does answer, he demonstrates an awareness of history, a sense of long-term strategy and a sophisticated grasp of the United States’ place in the grand scheme. It might not have been Gibney’s intention, but one gets the sense that, with people like Hayden in positions of authority, things won’t get too bad.

The title, “Zero Days,” refers to areas of vulnerability that a hacker can exploit, but the warning of a grim future is implicit. The film is a two-hour investment and the rewards are a handful of facts and ideas that could have been expressed in half that time. But those who want more detail will find it here.

 

Mick LaSalle is The San Francisco Chronicle’s movie critic. Email: mlasalle@sfchronicle.com. Twitter: @MickLaSalle

 

Zero Days

ALERT VIEWER

Documentary. Directed by Alex Gibney. (PG-13. 116 minutes.)

To see a trailer for “Zero Days,” go to https://youtu.be/Lq11OUKSDnU.