A senior U.S. official said here Monday that differences between Washington and Tokyo over relocating American troops in Japan will not be essential in the forthcoming Obama's visit to the country. Speaking to reporters in a conference call, Jeffrey Bader, U.S. President Barack Obama's top adviser on Asian affairs said that 'I don't see the Okinawa base issue being a dominant or essential issue on the visit.' 'I think that there will be ongoing discussions beyond the visit during which we will work out the differences,' Bader said. Some 47,000 American troops are based in Japan and more than half of them in Okinawa. The United States and Japan agreed in 2006 that the Marine airfield in Futenma, a crowded city on Okinawa, would be relocated to another part of the island. But Japan's government asked to do some changed about the agreement after August elections. In addition, Okinawans are trying to move the military base off the island entirely. However, the Obama administration has insisted that Japan's new government led by Prime Minister Yukio Hatoyama stick to the pact. Obama is due to arrive in Tokyo and have talks with Hatoyama on Friday. 