A dispute over a replacement facility for Futenma air base on Japan's southern island of Okinawa… is seen as key to the realignment of U.S. troops in Japan.

[Koichi Nakano, Assoc. Professor, Sophia University]:
"I think that the U.S. government is also having a hard time understanding where Hatoyama wants to lead the bilateral relations. And as a result, I think they are having some difficulties involved between the two countries, particularly on the issue of the relocation of U.S. bases in Okinawa."

Newly-elected Japanese Prime Minister Yukio Hatoyama pledged to forge more equal ties with Washington.

Hatoyama said before his party’s election victory in September, that he wanted to move the base off Okinawa to ease the burden on residents there.

But U.S. officials say they want to push ahead with a 2006 deal to move it from the crowded city of Ginowan in central Okinawa to a more remote site by 2014.

Hatoyama has said that he had no plan to decide by the time of Obama's trip -- or to say when he would make up his mind.

[Yoichi Iha, Ginowan City Mayor]:
"We would like to ask President Obama to give up building another military base that would destroy the environment, as well as to solve the issues of the existing Futenma air base, which poses extremely danger to local residents."

Okinawa hosts about half of the 47-thousand U.S. military personnel in Japan.

Many Okinawa residents have long resented what they see as an unfair burden for maintaining the security alliance.

[Katsuzo Shirane, Retired Office Worker]:
"I don't see any progress made since Obama became president with regard to peace and U.S. bases in Japan."

The Marine base row in Okinawa coincides with deepening questions about how China's rising military and economic clout will reshape security ties.