Obama Asia tour: China watches from across water

US President Barack Obama has left Washington for a week-long tour of Asia as part of what the White House is calling an "eastward rebalancing" of US foreign policy.

Mr Obama is set to visit Japan, South Korea, the Philippines- but not China.

It comes at a time when the country's growing naval power is worrying its neighbours.

Carrie Gracie reports on the obsession gripping China, and meets one man who built his grandson a 12m (39ft) scale aircraft carrier model.