A hacker claiming to be the president of a Hawaii-based anti-nuclear reactor group threatened via Twitter to carry out a "second wave of destruction" Sunday -- having exposed floor maps and other facility information from reactors in the southeast of South Korea.
The latest of several posts since last week also warned residents near the plants in question to keep their distance over the coming months.
But while acknowledging that leaked documents do appear to be from Gori and Wolsong nuclear power plants, Vice Energy Minister Lee Kwan-sup insisted the information was already readily available.
"One cannot launch an attack with such information," Lee said, adding that "a nuclear expert could easily obtain such information using Google's search engine."
His comments support the claim of nuclear officials, who insist that any leaks could not have occurred since April of last year, when local power plants' networks were isolated -- classified information is not available via the Internet.
But Lee did reveal that prosecutors are investigating as the government does not know "what the true intentions of these people are."
Protests against the construction of new reactors, as well as the handling of old reactors and nuclear waste, have been a common feature in South Korean society in recent years.
Seoul is not able to reprocess nuclear waste under an existing agreement with the U.S. -- while the country relies on its existing 23 reactors for around 30 percent of its energy needs.
The government has also been attempting to step up its cyber defences after accusing North Korea of a massive hacking attack last year, which temporarily crippled banks and media outlets.
As with the recent infiltration of Sony Pictures, Pyongyang maintains its innocence.