President Barack Obama is heading into a day of heavy diplomacy in his native Hawaii with some of the United States' most important and complicated allies, as he starts a nine-day tour of the crucial and growing Asia-Pacific region with domestic concerns front and center. Obama, who arrived late Friday after flying from San Diego, was to meet Saturday on the sidelines of a US-hosted economic summit with Chinese President Hu Jintao, Russian President Dmitry Medvedev and Japanese Prime Minister Yoshihiko Noda. Trade was also at the top of the agenda as Obama was to meet with leaders from eight Asian nations that are the US partners .With Obama pledging to double US exports, the White House hopes to show progress at the summit on the deal, the next trade focus for the administration following long-delayed approval of a free-trade agreement with South Korea. Obama also was to meet with US business leaders Saturday to highlight the importance for interests back home of the Asia-Pacific region. The 21 nations that make up the Asia Pacific Economic Cooperation forum account for 44 percent of world trade, and American business leaders are working eagerly to boost ties with them. “The trade that the US does with the Asia Pacific supports millions of American jobs,” Ben Rhodes, a White House deputy national security adviser, said. Japan has indicated interest in joining the other eight nations negotiating with the US on the Trans-Pacific Partnership, though hurdles remain, and that is sure to be a topic when Obama has his first meeting with Noda, who took office in September. In Hu and Medvedev, Obama encounters two leaders with whom he's sought close relations despite fraught histories between the US and those countries, with disagreements on human rights, territorial disputes, economics and other issues. For the president, the challenge is to maintain those ties while also pushing US priorities.