President Barack Obama will need to employ some deft diplomacy in order to achieve his aims during his tour of Asia, which begins today (November 12th) with a trip to Japan.Relations between the US and Japan have become frayed in recent months due to ongoing negotiations about the development of a new American military base on the island of Okinawa.Meanwhile, the looming threat that China poses to Japan's position as the world's second strongest economy has also raised fears that the US will neglect its trade relations with Tokyo."I want to make this a summit that shows the importance of Japan-US relations in a global context," said Japanese prime minister Yukio Hatoyama, speaking to Reuters ahead of the arrival of the president later today.Following his 24-hour visit to Japan, Obama will then move on to Shanghai, where he has scheduled three days of talks with Chinese premier Hu Jintao and other senior officials.Prominent on the agenda will be China's exchange rate policy and the artificial weakness of the renminbi against the dollar.