The Asahi Shimbun, quoting unnamed sources in Washington, reported on its website that Mr Obama wanted to show commitment to the US-Japan alliance by picking a high-profile ambassador well before taking office.

Nye, a professor at Harvard University, coined the term 'soft power' to describe how a nation or leader succeeds not only through the use of force but by appearing attractive in the eyes of the world. Outgoing President George W. Bush has often been faulted for neglecting soft power.

In an opinion piece last year, Prof Nye wrote of a sense of 'malaise' in relations between Tokyo and Washington due in part to Japanese perceptions that the United States cared more about a rising China.

Prof Nye said the United States could make Japan 'a much more equal and important ally' by focusing on soft power. Japan, officially pacifist since the end of World War II, could join Washington in fighting new threats such as climate change and pandemics, he argued.

US presidents have often picked high-profile ambassadors to Japan including former vice-president Walter Mondale, ex-House speaker Tom Foley and former Senate majority leaders Mike Mansfield and Howard Baker.

Relations between the Pacific allies have recently seen hiccups as conservative Japanese politicians voice unease at US concessions to North Korea under a nuclear disarmament deal. -- AFP