James Franco, left, and Seth Rogen in the canceled file "The Interview." (Ed Araquel/Columbia Pictures via Associated Press)

THE CYBERATTACK on Sony Pictures Entertainment has taken an even more disturbing turn. First it demonstrated how cyberthieves can raid a company’s most valuable trade secrets. Now it has escalated into a blatant terrorism threat by a group linked to North Korea and an assault on the freedom of speech directed from a capital of totalitarianism. Both the cyberattack and the coercion are unacceptable and cannot go ­unanswered.

According to news reports, the U.S. government has determined that a group in North Korea, or one sponsored by it, broke into Sony Pictures’ networks in retaliation for the studio’s production of a comedy depicting the assassination of leader Kim Jong Un. Sony Pictures hastily withdrew the film from theatrical release after the same hackers threatened theaters. We’ve never been wild about the widespread comical treatment of Mr. Kim; he may have a funny haircut, but there is nothing funny about the gulag where hundreds of thousands of Koreans have been condemned to slavery and death. Still, the canceled movie, “The Interview,” shouldn’t be judged without being seen — and whatever its merits, the method of its demise should ring alarm bells everywhere.

The most serious threat is to free speech, a pillar of democracy that protects a screwball comedy in which a foreign leader gets his head blown off, just as it protects an artist who draws a blasphemous picture of a religious figure. These crudities may rise or fall in the market of public opinion, but bans are not the right response. Satire cannot be censored, even when it is offensive. This is a principle entirely alien to Mr. Kim, who presides over one of the most rigidly controlled prison-states on the planet.

The cyberattack on Sony Pictures by a group calling itself Guardians of Peace looted sensitive trade secrets from a U.S. subsidiary of a global conglomerate. The studio is not alone in its vulnerability. Congress has tried but failed to approve legislation that would have allowed the federal government to work more closely with the private sector to protect corporate networks. We hope the next Congress will act soon. Not only movie studios but also electric utilities, banks and other essential corporate actors are vulnerable.

Meanwhile, the United States cannot let Mr. Kim intimidate movie theaters into silence nor allow his terror threats to succeed. Nor can Sony Pictures or U.S. movie theaters be expected to stand up to the threat unaided, even if it is unsettling that the picture was withdrawn so quickly. Perhaps posting “The Interview” to YouTube, so that billions of people could watch for free, would be one element in a fitting response.

The nation would not tolerate a ballistic missile landing in a movie lot; how should it respond to a cybermissile and a direct threat of violence? President Obama has signed a directive laying out criteria for the use of U.S. cyberforces for offense and defense. We hope he is reading it anew today.