The U.S. government took the unprecedented step last Friday of publicly revealing that North Korea led the cyberattack against Sony Pictures Entertainment and vowing a proportionate response against Pyongyang.

On Nov. 24, an entity calling itself the Guardians of Peace broke into the computer system at Sony Pictures Entertainment, leaking employee emails, unreleased movies and other sensitive information. It also virtually destroyed the company’s computer system. North Korea was seen as a possible suspect from the beginning as Sony was due to release “The Interview,” a comedy about an attempt to assassinate North Korean leader Kim Jong-un, on Christmas Day, and North Korea had not hidden its displeasure.

Then came the warning of 9/11-like attacks against theaters running “The Interview.” That warning from the cyberattackers led to Sony’s decision to cancel the movie opening last Wednesday after major cinema chains in the United States decided not to screen it.

In his year-end press conference last Friday, U.S. President Obama chided Sony for canceling the film’s release and rightly so.

By caving into the threat, Sony has transformed the hackers into cyberterrorists. Terrorists feed on fear, terrorizing the public to accomplish their goals. In this case, the threat of a terrorist attack, although seen to have little credibility by the authorities, succeeded in canceling the screening of a comedy. Sony has set a dangerous precedent by allowing itself to be controlled by terrorists. What next? A threat to blow up a broadcaster for producing a documentary that a group finds not to its liking?

The Sony attack has ushered in a new era of cyberwarfare with the U.S. government pinpointing the culprit and promising retaliation, both of which are unprecedented moves. The strong government-level response stems from the fact that this particular attack is perceived as a threat to freedom of expression, a value that is quintessentially tied to what it means to be American. This was not a case of industrial theft, but became an attack on the very fabric of American life when the hackers threatened 9/11-like attacks on theaters running “The Interview.” The FBI, in a statement, called cyberthreats “one of the greatest national security dangers.”

As for the yet unspecified “proportionate response,” a countercyberattack is a possibility that immediately comes to mind but one that is unlikely. Such a move risks further escalating tensions on the Korean Peninsula. Also, security experts claim that launching a counterattack via the route through which Sony was infiltrated could be counterproductive.

Further economic and banking sanctions could be imposed, but the North Korean regime is already under one of the strictest sets of sanctions in the world and the isolated nature of the state limits the impact of such sanctions.

Another option is relisting North Korea on the State Sponsors of Terrorism list. North Korea was removed from the list in 2008. North Korea, already under strict sanctions, would not be heavily impacted by being added to the list again, but the listing would have symbolic significance at a time when the country is facing international scrutiny over its human rights record.

The latest cyberattack and the U.S. government’s response to it has highlighted the need to formulate a global agreement on countering such attacks and threats. South Korea, whose banking and media institutions were the targets of a large-scale North Korean cyberattack last year, and Japan have pledged cooperation in the investigations. China, whose cooperation is essential as North Korean hackers used IP addresses in the country, should similarly cooperate in the investigations.