BERLIN -- A German military officer used an unsecured phone line at a Singapore hotel to join a conference call that was hacked by Russians and leaked to the public, Germany鈥檚 defence minister said Tuesday.

The fallout from the leaked audio tape, which features four high-ranking German air force officers discussing hypothetically how Taurus long-range cruise missiles could be used by Kyiv against invading Russian forces, has embarrassed the German government and further increased tensions between the two countries.

鈥淣ot all participants adhered to the secure dialling procedure as intended,鈥 German Defence Minister Boris Pistorius said as he briefed reporters in Berlin on the initial results of an ongoing investigation.

The minister said that the officer in question, whose name he did not give, had participated in the Singapore Air Show, which was attended by high-ranking military officers from across Europe, and then dialled into the WebEx call using either his mobile phone or the hotel's Wi-Fi but not a secured line as is considered mandatory for such calls.

鈥淔or the Russian secret services, it was a real find. ... Targeted hacking took place in the hotels used across the board," Pistorius said. "It must therefore be assumed that the access to this (phone) conference was a chance hit as part of a broad, scattered approach.鈥

Pistorius said the investigation was ongoing, overall security had been increased and preliminary disciplinary proceedings were being considered, but that severe personal consequences were unlikely.

鈥淚 will not sacrifice any of my best officers to Putin鈥檚 games, to put it very clearly,鈥 he said, referring to Russian President Vladimir Putin.

The 38-minute audio leak was posted by Margarita Simonyan, chief editor of the Russian state-funded television channel RT, on social media on Friday, the same day that Russian opposition leader Alexei Navalny was laid to rest after his still-unexplained death two weeks ago in an Arctic penal colony. The recording also surfaced just weeks before Russia鈥檚 presidential election.

While German authorities have not questioned the authenticity of the recording, Chancellor Olaf Scholz said last week that delivering those weapons to Ukraine was not an option 鈥 and that he does not want Germany to be drawn into the war directly.

However, Russia鈥檚 Foreign Ministry on Monday threatened Germany with 鈥渄ire consequences鈥 in connection with the leak. It did not elaborate.

Relations between the two countries have steadily eroded since Russia invaded Ukraine two years ago.

In the leaked audio, four officers, including the head of Germany鈥檚 air force, Ingo Gerhartz, can be heard discussing deployment scenarios for Taurus missiles in Ukraine before a meeting with Pistorius.

The officers said that early delivery and rapid deployment of Taurus missiles would only be possible with the participation of German soldiers. The officers said training Ukrainian soldiers to deploy the Taurus on their own would be possible, but it would take months.

The recording also shows the German government has not given its OK for the delivery of the cruise missiles sought by Ukraine.

Pistorius said Tuesday that while the damage caused by the leak was severe, 鈥渢he mistake is still being worked through and we must now turn our attention back to more important tasks," such as how Germany and its allies can continue to help Ukraine fight Russia.

There had been a months-long debate in Germany about whether to supply the Taurus missiles to Ukraine as Kyiv faces battlefield setbacks until Scholz said last week Germany wouldn't deliver the missiles. With military aid from the United States held up in Congress, Germany is now the second-biggest supplier of military aid to Ukraine after the U.S., and it is further stepping up its support this year.

Pistorius pointed out that while the damage done by the actual content of the leaked audio was 鈥渕anageable,鈥 Russia's real success was that with the leak it set the agenda for what is being discussed in Germany, and 鈥渢hat's exactly what Putin wants to achieve.鈥