A British military official said: "If you are looking for a nuclear deterrent, it makes sense to acquire a submarine fleet. They are the best solution for nuclear power projection because they are difficult to detect and destroy."
Jason Alderwick, a maritime defence analyst at the International Institute of Strategic Studies, said: "Submarines are potent platforms and will be a key factor in any dispute over Taiwan or the Moluccas."
Indonesia's military spokesman, Rear Adml M Sunarto Sjoekronoputro, told The Sunday Telegraph that increasing naval power was critical for a country of 17,000 islands. "To secure our borders, two outdated submarines are not enough," he said. "We will buy new submarines step by step, as the economy allows."
The unspoken reason, spelled out in the Australian report, for the growth in submarine power is China, with which Indonesia has had uneasy relations for 40 years.
Since 1996, when the United States sent two carrier battle groups to Taiwan to deter -Chinese aggression, China has invested in weapons to boost its naval power. President Hu Jintao told Communist Party delegates last year he wants a navy prepared "at any time" for military action.
The US Office of Naval Intelligence says China is intent on building five strategic nuclear-missile boats, equipped with 5,000-mile range JL-2 missiles, which will give it an arsenal of 60 strategic nuclear missiles at sea, each with multiple warheads.
The first will go to sea next year, and the first two of a new class of nuclear-powered attack submarines will enter service this year. Chinese defence spending will increase 17 per cent this year to £23 billion - the 19th year of double-digit growth.
Last November China shifted its defensive posture, from the Mao doctrine, which envisaged destroying enemies within the borders of China, to one that would protect the homeland offshore.
The US Department of Defence's recent Military Power Report on China concluded that the country was working on a combat air wing for a future aircraft carrier, capable of projecting power far into the Pacific.
Robert Karniol, the Asia-Pacific bureau chief of the magazine Jane's Defence Weekly, said: "There are deep suspicions around the region fed by China's lack of transparency.
If you build up offshore capability your intention may be defensive but the equipment can be used for offensive action. As military capabilities grow more sophisticated offshore, the possibility of misunderstandings and small incidents building into something serious is heightened."
Vice-President Dick Cheney signalled the US response in February when he visited Guam, the 30-mile long Pacific island dubbed America's "unsinkable aircraft carrier".
He hailed the arrival of two Los Angeles-class nuclear-powered attack submarines, with a third due later this year. Guam's Apra Harbour is under refurbishment to accommodate Trident nuclear subs.
But Chinese submarines may be shifting the balance of power. Mr Karniol said: "The Chinese have made clear they retain a military option on Taiwan. The consensus is that the Americans would not be able to prevent an invasion. They would be able to move and defeat it but they wouldn't be able to stop it happening."