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It begins with a Farsi-speaking voice scratching out of the static. “Tavajjoh! (Attention!),” he demands three times, before reading a steady stream of numbers: “Six. Four. Zero. Nine. Three. Nine.”
The ghostly broadcasts have been sent out regularly over long-distance short wave radio from a transmitter somewhere in western Europe since the hours after the first US and Israeli strikes on Iran on February 28.
It is a tantalising sign that the shadowy intelligence battle within Iran may have entered a new phase. Former US intelligence officers said the broadcasts were likely an emergency measure enabling Washington to maintain contact with agents within Iran.
“It is likely that this is backup communications for our sources inside Iran. These are people that you cannot afford to be out of contact with,” said John Sipher, a former CIA station chief in Moscow. “If you are going to war, it is a perfect fallback.”
The broadcast was briefly drowned out within days by a barrage of electronic beeps and chirps — a sound that experts said was probably an attempt by Iran to jam the broadcasts. But the mysterious male voice quickly hopped on to a new frequency and began reading out its numbers once again.
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It appears to be a so-called number station: a short wave transmission used by intelligence agencies to send encrypted one-way orders and instructions to spies armed with radios and notebooks to translate the numbers into messages.
The station — first spotted by short wave trackers who christened it V32 — is the first to have been identified broadcasting in Farsi in a quarter of a century. One briefly went live during the US invasion of Afghanistan in 2001; the number patterns used by that station led some watchers to suspect it may have been Russian-operated.
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The Farsi broadcast launched last month is now running twice daily at 5.30am and 9.30pm Iranian time, lasting for about an hour and a half each time.
The broadcasts have not been traced to a specific source, and with the station accessible to anyone with a short wave radio, it is not possible to know who is listening. But this is precisely what makes a number station attractive.
Unless the operators make errors, or spies are caught in the act of transcribing messages, it is virtually impossible for counter-intelligence agencies to do anything about number stations beyond jamming their frequencies.
“It is not a coincidence that it started on the day the war began,” said Chris Simmons, a former US counter-intelligence officer who spent years hunting spies using such stations to receive orders from Cuba.
“If someone is out there risking their life, then you have to give them the simplest possible tools, as well as something that is concealable and plausible to explain away.”
The station launched as Iran’s government severely curbed the country’s internet links with the outside world, as it has previously done in moments of crisis — and as the conflict with the US and Israel would have led to an especially perilous moment for any agents in the country.
Sipher, who was trained to use number stations and has also been a lead instructor on the CIA’s clandestine training programme, said: “If the internet goes down, or the phone services are cut off, you still have a means to contact your sources.”
Simmons said his experience hunting Cuban double agents in the US had taught him how a single well-placed individual receiving orders through such a system could wreak havoc.
Number stations could remain an option for agents in the field for many years, even when fresh training or new communications methods were too dangerous to consider, he said. Messages were often repeated so the agent would only need to take the risk of listening once, he added.
The station could be communicating instructions to agents in the field that they are being activated, or orders to leave the country or head for meeting points, the former agents said.
Simmons said number stations were used to communicate with only the most crucial intelligence assets. Their use can be relatively easily concealed: radio dials can be switched away within seconds and the one-time pads quickly destroyed. More modern equipment could attract suspicion, he said, or leave traces that can be forensically examined.
“If you have had a radio for years, and everybody knows that you have it, why would they think that you are a potential spy? You could be hiding in plain sight,” Simmons added.
Members of Priyom, a short wave monitoring group, have triangulated the rough location from which V32 is being broadcast by calculating the time its signal takes to reach various receivers. Those results pointed towards western Europe.
Number stations are among the rare cases in which the work of intelligence agencies surfaces into plain view. The phenomenon has declined since the end of the cold war, but it has not totally disappeared. Poland, Russia, Taiwan and North Korea are among a handful of countries thought to be responsible for regularly scheduled number stations.
V32 has little character compared to some others, such as V13, also known as New Star Broadcasting. That station transmits from Taiwan and is audible across east Asia. It greets its listeners with a flute melody and signs off: “Thank you for listening, and we wish you health and happiness.”
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They are thought to be directed at agents operating under deep cover in the most challenging circumstances.
The CIA has reportedly struggled to maintain intelligence networks within Iran, considered to be one of its most difficult operating environments because it lacks a US embassy. There is a particular need for fail-safe communication mechanisms that can be activated when other means of contacting sources become difficult.
“If you spent time working on Iran or North Korea, then these things are not unusual,” Sipher said. “It is one of those old-fashioned things that works.”
Other explanations for V32 have also been suggested. Robert Gorelick, a former CIA station chief in Lima and Rome, speculated that militant Iranian dissidents could be using V32 to communicate with networks inside Iran.
“It is an effective, cheap and very secure way of communicating,” Gorelick pointed out. But dissidents would be unlikely to be able to operate such a station without the tacit approval of a western intelligence service.
V32 could alternatively be designed to stoke paranoia within Iranian counter-intelligence circles by suggesting there are high-level agents in Tehran waiting for orders from Washington or Tel Aviv.
“This adds to the pressure on [Iranian counter-intelligence]. If you proposed this to me, and I was sitting in Langley, I would say: ‘Let’s do it,’” Gorelick said.
Tehran “would probably put some cryptographers on the numbers that are coming in to see whether they can discern any patterns”, he said.
Enthusiasts, meanwhile, have tuned in to seek clues to the identity of the station, feverishly speculating as to its function. They debate whether the broadcast is pre-recorded or is read out live. Listeners have detected sounds similar to error messages from Windows 10 and shuffling sounds that resemble an operator moving a microphone.
“It is old school,” said Tony Ingesson, a counter-intelligence expert at Lund University who has studied number stations. “You still have this arsenal of ancient communications techniques that work just as well now as they did before.”
Illustration by Ian Bott
