The Security Service of Ukraine, more widely known as the SBU, has become the country’s primary weapon in its information war with Russia. As well as feeding intelligence to military units to guide their battlefield operations, the shadowy organisation also has been disseminating vast amounts of propaganda, neutralising enemy “bot farms” and arresting internet users who support Russia.

While much counterintelligence work is done behind closed doors, its agents are engaged in a new type of electronic warfare: intercepting and publishing Russian military communications online.

The reliance of invading Russian soldiers on insecure mobile phones and high-frequency radios has made many of their conversations vulnerable to eavesdropping.

Defence experts say that early Russian attacks on Ukrainian 3G and 4G telephone masts unwittingly knocked out their