'We are dealing these days with so many people who are connected to this technology, some might call it the internet generation,' Admiral Mullen, the current chief of naval operations, told sailors in a podcast.

'The sound of a person's voice can be more powerful than just the written word. The old ways of just launching a press release or sending out a naval message just won't work any more. A promise I made to myself was to find new ways to have a conversation, not only with navy personnel but with America about what we're up to.'

Admiral Mullen's responsibilities as the country's senior military adviser, of course, will run to far more than merely exploiting new technology to keep American citizens 'on message'.

He is charged with the task of guiding his fighting personnel away from the mistakes made in Iraq and Afghanistan and towards a brighter future, with public confidence fully restored in the services.

It was that priority that led Dr Gates to dispense with outgoing chairman General Peter Pace, seen by many as too closely involved in the recent failures of the Middle East, and turn to Admiral Mullen. As a naval officer, Admiral Mullen, 60, is in the branch of the armed services that has had the least to do with a war that has so far cost the lives of more than 3,500 personnel.

It was a surprisingly sudden switch of direction by the defence secretary, who insisted that he was replacing General Pace reluctantly because he wanted to avoid a 'backward-looking and contentious' confirmation hearing for a second two-year term, set to begin October 1.

'I think that a divisive ordeal at this point is not in the interest of the country or our men and women in uniform,' he said. 'I wish it were not the case, I wish it were not necessary to make a decision like this.'

But once that decision was made, he said, his consultations with Gordon England, the deputy defence secretary, quickly led him to Admiral Mullen, with Marine Corps General James Cartwright his recommendation for vice-chairman.

'I have become well acquainted with Admiral Mullen over the past six months and believe he has the vision, strategic insight, experience and integrity to lead America's armed forces,' Dr Gates said.

Others who know Admiral Mullen professionally say he is a solid pair of hands, personable and intelligent but not frightened to take a tough decision when necessary. Even General Pace had appreciative words for his likely successor: 'He is a very smart, strategic thinker,' he said. 'I think he has a view of the interests of the services as a whole, a broad view of what the needs of the services are and of the nation.'

But Admiral Mullen despite holding such a high-profile job in the US Navy hierarchy since July 2005, remains largely unknown in the average American household, partly because the nation's military focus is mostly on the progress of marines and army soldiers in Iraq. A common reaction upon hearing Dr Gates make his nomination last week was: 'Admiral Mike who?'

'He's certainly done a good job as chief of naval operations, written a number of policy papers and been successful in a continuous application of energy to change the navy when there are no other navies to fight,' said Thomas Keaney, an American defence expert and executive director of the Merrill Centre for Strategic Studies at Washington's Johns Hopkins University.

Professor Keaney believes that one of Admiral Mullen's most attractive tributes, in the eyes of the White House at least, is his desire to include foreign countries and their military assets in the global 'war on terror' and in peacetime endeavours.

Last year he unveiled his vision of a 'thousand-ship navy', in his words a 'global maritime partnership that unites maritime forces, port operators, commercial shippers, and international, government and non-governmental agencies to address mutual concerns.

'Membership in this 'navy' is purely voluntary and would have no legal or encumbering ties. It would be a free-form, self-organising network of maritime partners, good neighbours interested in using the power of the sea to unite, rather than to divide. The barriers for entry are low. Respect for sovereignty is high.'

When he explained his concept in Washington last autumn, pointing out how such international partnerships enhanced relief efforts after the 2004 Indian Ocean tsunami and the 2005 Pakistan earthquake, he 'hit a home run with the president', according to navy sources.

Whether he will be able to pursue that plan once he steps into his wider-ranging role remains to be seen, though Professor Keaney contends that Admiral Mullen likely pushed it forward more as a principle, 'something to show his idea on the need for a coalition for naval operations'.

'One phase of it is the thousand-ship navy, but more so what role does the US Navy play in the world?' Another question will be whether Admiral Mullen can still see through his aim of expanding the navy from its present 277 ships to more than 300, which would be the first major expansion of the fleet since the end of the cold war.

If confirmed, he will become only the fourth naval officer to become chairman of the Joint Chiefs of Staff, but would prefer to see it as a 'desk' job in name only. 'I am convinced that the most powerful way to spend your time as a leader is not in front of people, above people or on a computer or on a cellphone with people, it is down on the deck plates, as they say in the navy, is where you can listen and learn from people,' he said.

He became popular with naval colleagues of all ranks for policies of openness, accountability and support for spouses and relatives. 'Our spouses serve as we serve every bit as much. They do not bear the arms, but their open arms provide strength and comfort.' Admiral Mullen himself is a family man who has been married for 36 years, has two sons also in the US Navy. He enjoys travelling, golf, fly-fishing, swimming and weightlifting.

Senate Democratic leader Harry Reid has called on Admiral Mullen and General Cartwright to be men of steel. 'Senators will be looking very closely to make sure they are committed to changing course in Iraq,' he said.