New Aukus drone tech to protect critical undersea cables as Marles warns: ‘seabed is a battlefield’

Minister at Singapore defence summit also reveals Australia to buy only secondhand Aukus submarines from US

The defence minister, Richard Marles , has said the “seabed is a battlefield” in a combative speech urging Beijing to be more transparent about its maritime operations, and taking aim at weak international controls over so-called “shadow-fleet” vessels.

The warning came as the US, UK and Australia announced a new Aukus project to develop new underwater drone technology to protect undersea cables.

The same announcement also revealed that Australia would buy three secondhand Virginia-class submarines from the US under Aukus, instead of a mix of old and new, in a move to “simplify supply chain management, operational and maintenance requirements, and maximise cost efficiencies”.

Speaking at the Shangri-La Dialogue in Singapore, Marles said undersea internet cables – “the arteries of modern civilisation” – were being cut at an unprecedented rate, with island nations like Australia acutely vulnerable.

“The seabed is becoming a battlefield. The shadow fleet is becoming a weapon,” he told Asia’s largest defence summit.

“Over the past 18 months, we have witnessed a series of attacks against subsea critical infrastructure at a scale and frequency that is historically unprecedented.

“This is not speculation. This is a documented pattern of behaviour. And we must reckon with it honestly.”