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In the hours after the first US and Israeli attacks on Iran, with the world’s attention focused on the conflict, a group of amateur sleuths noticed a series of unusual messages on the airwaves.
Broadcast in Farsi, the short-wave radio signals were accompanied by seemingly random numbers.
They recognised them as spycraft that came into common use during the Cold War. Numbers stations, as they are known, would relay strings of numbers which could be decoded by an intended recipient with a short-wave radio.
The near-zero likelihood of the broadcasts being deciphered made numbers stations a feature used by all sides of the shadow intelligence battles of the time. No government has officially admitted or denied using them.
The emergence now of the first detected broadcast of a Farsi-language numbers station broadcast has generated theories about their origin and purpose among the community of enthusiasts and intelligence experts.
In the broadcasts, the numbers are followed by a pause then the word tavajjoh, meaning "attention” in Farsi, which is then repeated three times.
It was thought the broadcasts, given the name V32 by the numbers station community, emanated from central Europe and were aimed at Iranian sleeper agents perhaps primed to attack US and Israeli targets.
But the signals began to be jammed by the Iranians themselves, using a frequency aimed at anti-regime broadcasters. Further analysis placed the signals as coming from southern Europe or the Middle East, adding another dimension to the mystery.
Jonathan Hackett, a former US Marine Corps intelligence officer, told The National it would “not make sense” for the Iranians to use a numbers station.
“My thought is that this is not a regime-controlled station and is instead something probably coming from the US or Israel to activate something set up in advance to assist with enabling clandestine activities in support of the opening salvo of the war effort,” said Mr Hackett, who has held positions at the US Defence Intelligence Agency and National Security Agency.
“This could be to alert recruited assets to seek safety, instruct support agents to put necessary items in place, or safe house managers to prepare for the former two options, and myriad other purposes.”
In keeping with the covert nature of intelligence work, a theory has also emerged that the US and Israel could be trying to bluff the Iranian regime into believing there is a network of agents in Iran on standby.
Akin Fernandez, a numbers stations enthusiast who has been researching the field since the early 1990s and is considered one of the world’s leading experts, said he “wouldn’t be surprised if the Farsi language is used as a provocation”.
Mr Fernandez's Conet Project has catalogued numbers stations and produced a series of CDs and downloads. One recording was sampled in the 2001 film Vanilla Sky starring Tom Cruise.
He told The National it is possible “there is nobody in Iran who's receiving these signals and it is just there to terrify the Iranian government that there's a whole bunch of sleeper cells that have been infiltrated into Iran over many years”.
“We know that [Iran] doesn't want those transmissions to be heard. And so whether it's real sleeper cells there or not, somebody has been motivated to go and block them.”
Whoever is behind the broadcasts is likely to have “access to a big transmitter”, which only nation states currently possess, said Mr Fernandez.
Priyom, an organisation which carries out research into numbers stations, states that if “V32 is a legitimate intelligence operation aimed at activating local assets in Iran, the question of having a network of infiltrated agents, and being able and ready to launch a pre-arranged numbers station within 12 hours of the beginning of the war, suggests the two prime candidates who prepared and launched the war: the US and Israel”.
It also speculates that the idea “that numbers stations are just a gigantic, fake psychological operation, to impress, scare an adversary and sow paranoia within it” is part of the mythology and conspiracy theories that surround numbers stations.
Secret codes
Numbers stations sprang up after the Second World War, when amateur radio enthusiasts started to notice strange broadcasts that often began with music, noises or spoken words.
One station, thought to be run by British intelligence from Cyprus, played the first bars of the folk song The Lincolnshire Poacher before numbers were read out.
A machine known as a speech/Morse generator was developed by East Germany's Stasi intelligence service for sending coded messages through Soviet bloc numbers stations.
The system works by using a one-time notepad. A series of what appears to be random numbers is generated by the machine, of which two copies are made.
The agent in the field has one copy of the random sequence of numbers printed on a small notepad. The spy agency has an identically-numbered pad.
The numbers relate to letters, so the sequence read out by the radio station can be decoded into a message using a mathematical formula.
Each pad is used once for each broadcast before being disposed. This changing of the code makes it nearly impossible for an attacker to crack the message.
Since the end of the Cold War, the US has alleged that Cuban spies it has caught relied on numbers stations broadcast from Havana.
Mr Fernandez said the numbers stations were actually more effective than encrypted messaging platforms.
"So-called modern methods of communication are not as effective and not as private as a short-wave transmission on numbers stations,” he said.
The broadcasts from V32 can still be heard twice a day in southern Europe but is now very weak in central Europe, according social media posts by numbers station enthusiasts.
Mr Fernandez said the numbers are being read out in groups of five rather than continuously, which all adds to the mystery.
"So this is some kind of work in progress as they're going along. Why would they change the format of the transmission, after days of doing it one way?”
Enthusiasts will continue to monitor the broadcasts as they seek answers.
