BERLIN - The audio of a German high-level military discussion on Ukraine was intercepted by Russia because a participant had joined the Webex call from an unsecured line from a hotel in Singapore, said German Defence Minister Boris Pistorius on March 5.

Russia had likely intercepted the discussion among senior German air force officials by chance via widespread surveillance, he added, as he presented initial results of an investigation into the leak, which has embarrassed Germany and prompted questions about its intelligence security.

German communications systems had not been compromised, Mr Pistorius said as he addressed the leak from Berlin following an investigation by military intelligence.

Russian media last week published an audio recording of a meeting of the German officials held on the Webex platform discussing the delivery of Taurus missiles to Ukraine and a potential strike by Kyiv on a bridge in Crimea.

“Our communication systems have not been compromised,” Mr Pistorius said. “The reason the air force call could nonetheless be recorded was because of an individual’s operational mistake.”

The participant had dialled in from a hotel room in Singapore where an air show took place. The individual was identified as Brigadier-General Frank Grafe, according to a transcript posted by Ms Margarita Simonyan, editor-in-chief of Russian state broadcaster RT on March 1. He was one of four high-ranking German air force officers on the call.

The Feb 20 to 25 Singapore Airshow attracted high-ranking European military officials, making it a target for Russian security services.

Mr Pistorius did not name the officer, but said he dialled into the Webex call using either his mobile phone or the hotel’s Wi-Fi network, and not a secure line as would be expected for such calls.

“For the Russian secret services, it was a real find... Targeted hacking took place in the hotels used across the board,” said the Defence Minister.

“So we must assume that the access to this Webex conference was a chance hit in the framework of a broad, scattered approach.”

The use of Webex for calls up to a certain security grade was authorised, he said, noting that it was not the off-the-shelf software but a specially certified one with servers in the Bundeswehr’s computing centres in Germany.

Still, Germany was investigating if issues were mentioned on the call that should not have been discussed on Webex, he said.

Mr Pistorius said Russia had leaked the call in a bid to create divisions in Germany and between the country and its allies.

In the call, German Air Force chief Ingo Gerhartz discusses with three high-ranking Luftwaffe officials the possible delivery of Taurus cruise missiles to Kyiv, which Chancellor Olaf Scholz has publicly so far firmly rejected, fuelling a public debate.

Asked if the leak could affect the position of Lieutenant-General Gerhartz, Mr Pistorius said if nothing further emerged in the probe, “then I am not going to sacrifice one of my best officers to (Russian President Vladimir) Putin’s games”.

Germany would take technical and organisational measures to ensure such an incident would not happen again, Mr Pistorius said, adding he had spoken on March 4 with his peers in partner countries who expressed their continued trust in Germany.

“Everyone knows about the danger of such eavesdropping attacks and know that you cannot ensure 100 per cent protection against them,” he said.

Germany’s allies have been reticent in their public reaction to the recording, although some British politicians outside government criticised German security measures.

Former British defence secretary Ben Wallace was quoted as saying by The Times that the incident demonstrated Germany was “neither secure nor reliable”.

The Kremlin says the recording shows Germany’s armed forces were discussing plans to launch strikes on Russian territory, charges Germany denies as “absurd”. REUTERS