North Korean spy Kim Hyon-hui, center, with her mouth taped, is taken from a plane in December 1987 upon her arrival in Seoul, South Korea, from Bahrain, after she bombed a Korean jetliner, killing all 115 aboard.  (Kim Chon-kil/AP)

A disastrous hack of Sony Pictures and the subsequent cancellation of "The Interview" has rightly been taken as a sign of the growing threat of cyberwarfare in the modern age. Many observers now wonder whether North Korea's actions (assuming it really is North Korea) constitute some new form of online terrorism.

That's a valid question, certainly. But it's important to note that while the online attack of Sony Pictures has been the most dramatic crime committed so far, the dramatic shelving of "The Interview" only came after a threat of actual, real-world terrorism.

"We will clearly show it to you at the very time and places 'The Interview' be shown, including the premiere, how bitter fate those who seek fun in terror should be doomed to," a message from the group claiming responsibility for the hack announced this week. "Remember the 11th of September 2001," the message added ominously.

It was only after this threat that "The Interview" was pulled from cinemas and Seth Rogen and James Franco, the film's co-stars, were pulled off of publicity appearances. To some extent, this decision was understandable. Sony Pictures did not want blood on its hands (for both moral and business reasons).

But there is another important question here: Was this threat ever actually credible? Some have expressed their doubts. Peter W. Singer, an expert on cybersecurity with the New America Foundation, is one of several people who have cast doubt on that. "We need to distinguish between threat and capability," Singer noted in an interview with Vice. "The ability to steal gossipy e-mails from a not-so-great protected computer network is not the same thing as being able to carry out physical, 9/11-style attacks in 18,000 locations simultaneously."

When thinking about this, its worthwhile to consider history. While North Korea's threats of violence have become frequently absurd and absurdly frequent over the last few years, the country really has been at the center of sometimes spectacular international terror plots before – though the nature of these plots and their frequency has changed significantly over time. Outside of incidents that could be described as terrorism but might also be thought of more along the lines of border disputes (such as the 1969 incident in which North Korean jets shot down a U.S. spy plane or the seizure of the intelligence-gathering ship Pueblo the year before), there have a number of other examples that fit quite easily in what we think of as terrorism these days.

For example, in 1968, a group of North Korean commandos dressed as South Korean soldiers attempted to storm the South Korean Blue House  and kill South Korea's president Park Chung-hee. In 1969, a North Korean agent hijacked the domestic Korean Air Lines flight YS-11 and held the passengers and crew hostage (39 passengers were later released, but 11 others were kept in North Korea). And in 1983, North Korean agents detonated a bomb in Rangoon, Burma, in an attempt to kill South Korean president Chun Doo-Hwan (Chun survived but 21 other people did not).

In addition to acts like these, North Korea kidnapped a vast number of foreign citizens in the 1970s and 1980s, including many Japanese citizens. A 2011 report from the U.S. Committee for Human Rights in North Korea found that at least 17 Japanese citizens and at least 25 citizens of other nations had been kidnapped over the years, sometimes in remarkably daring raids in their home nation. North Korea is also alleged to have sold weapons to terrorist groups and given support and asylum to members of terrorist groups, such as Japan's Red Army.

No doubt the most devastating terrorist action attributed to North Korea, however, is the bombing of Korean Airline flight 858. The plane, flying between Baghdad and Seoul, was destroyed as it flew over the Andaman Sea in 1987; all 115 people on board were killed. The bombing was believed to be designed to scare tourists away from Seoul's 1998 Summer Olympic Games. While North Korea has denied any link to the attack, one of the perpetrators of the was captured and admitted to her role in it (during interrogation, she had attempted to kill herself with a cyanide capsule like her partner, but did not die).

In hindsight, the bombing of Korean Airline flight 858 was a watershed moment for North Korea. While Pyongyang continued its antagonistic relationship with South Korea and the United States, working on its nuclear weapons program and engaging in relatively frequent attacks along its border with South Korea, it has not committed a comparable international terror act since and has renounced its support of terrorism (though incidents like the torpedoing of South Korea's Cheonan ship in 2010 – an attack which killed 46 people – seriously blurred the line).

What made North Korea shift away from acts like the Korean Airlines bombing? There's a variety of plausible scenarios. First, there was significant international pressure from the United Nations and the U.S., which placed North Korea on its list of State Sponsors of Terrorism (they were removed in 2008, though may well end up back on it now). But perhaps just as important was the the shifting nature of the world about that time: North Korea had long been propped up by the financial largess of the Soviet Union and emboldened by its geopolitical clout.

When the Soviet Union crumbled, North Korea was not only pushed into economic chaos but also true international isolation. China, its most important ally left, was slowly opening up to the West. It was unlikely to tolerate provocative terror acts from its "little brother."

The threats from the Sony hackers beg another question, however: Why would North Korea return to active threats of terrorism after almost three decades without it? As The Post's Anna Fifield notes, "The Interview" portrayed the very thing that the North Korean elite is genuinely terrified of – an assassination attempt on Kim Jong Un. Coupled with issues surrounding Kim's legitimacy and pressure from the United Nations over North Korea's  human rights record, it appears North Korea may have felt it necessary to lash out.

There's another factor, of course: North Korea may simply be changing with the times. It's historical terror attacks fit with the terrorism trends of the era – plane hijackings and assassination attempts. The cyberattacks of which it now stands accused were not possible for North Korea in the 1990s and 2000s, but now they are. North Korea likely sees these attacks as a way of closing the vast gap in military capability between itself and the United States. North Korea has also shown that it studies American culture. It's no doubt aware of how much the specter of the September 11 attacks hangs over the country, and it may also be aware of the horror caused by the mass shooting in a Colorado cinema in 2012.

The final, big question is whether North Korea actually issued the threat. That's a hard question to answer. The scenario Singer lays out, with attacks in thousands of locations, is clearly outlandish. But some kind of smaller attack is probably within the realm of possibility for North Korea (or really any foreign state). And while North Korea has never committed an attack on U.S. soil, the Sony hack does show that the country is capable of unprecedented acts.