South Korean spies find antiquated numbers game still safer
But South Korea's reliance on decades-old methods means it has a patchy surveillance record
As a scratchy rendition of Beethoven's Piano Sonata No 8 fades into a sea of shortwave radio static, a robotic female voice starts speaking in Korean.
"Number 1913, number 1913, incoming message," the voice says, before reading out seemingly random sets of numbers.
"68360, 75336, 80861, 94409, 03815," it continues in an eerily authoritative tone.
The broadcast, a method of sending one-way secret messages to spies, dates back to the French Resistance in the second world war and is still in use on the Korean peninsula, where human intelligence remains the most important way of gathering information.
Blanket electronic surveillance and satellite imagery offer only limited penetration in isolated North Korea, where the use of mobile phones and the internet is far below global standards. But reliance on antiquated methods and human sources has meant that the National Intelligence Service (NIS), South Korea's spy agency, has a patchy record on finding out what is going on in nuclear-armed and unpredictable North Korea, with which it is still technically at war.
But the agency scored a coup last week by informing the world that Jang Song-thaek, the powerful uncle of North Korean leader Kim Jong-un, had been removed from his positions.
"For cases like the dismissal of Jang Song-thaek or events within the Korean Worker's Party, we need human intelligence," said Yeom Don-jay, a retired NIS veteran. "Humans know the minds of humans best," said Yeom, who worked at the spy agency for three decades before retiring in 2004 after postings in Germany, Brazil and the United States.
The agency has been notoriously averse to any attempts at reform over the years and its current chief, Nam Jae-joon, has said a reform plan would leave its hands tied.
The radio messages have been used by the South for decades. "It's classic - the safest way to deliver messages, it leaves no trace," Yeom said.
The messages work by sending strings of seemingly random numbers over shortwave radio signals to an agent in the field, armed only with a radio, pen and an easily concealed pad with corresponding letters on it that can be used to decrypt the messages.
"The first time I heard the South Korean numbers station now known as V24 was probably in the early 1980s," said a radio hobbyist who only identifies himself by his call sign, Token.
Long-time listeners like Token say V24's unique power signature and signal strength place its origin somewhere south of the Demilitarized Zone that separates North and South Korea.
An official at the NIS who deals with media requests said he could not confirm anything related to the operation of South Korean numbers stations.
But hobbyists say the secret station is being used less frequently.
"In July, I received 62 messages, most of them in the first half of the month," said Token, who monitors the signals from his location in the Mojave Desert in the US. "However, in the first 10 days of November, I only received three. I have never seen traffic anywhere near this low. This station could be winding down operations."
A former South Korean commando who has worked behind North Korean lines said he had communicated with his handlers by radio and number codes.
"We had a morse code machine and a number pad. North Korean agents were using the same methods at the time," the commando said. "It still looks like a safe way to communicate."