TOKYO: A trip by Japan's foreign minister to Washington to try to soothe strained ties was up in the air yesterday as doubts simmered over whether a feud about a military base will be resolved before a visit by President Barack Obama.

The row over the planned repositioning of the US Futenma air base on Japan's southern island of Okinawa has ruffled relations between the two close security allies ahead of Obama's Nov12-13 visit.

The Democrats have pledged to steer a more independent course from Washington, raising concerns about the alliance, long central to security arrangements in a region home to both China and the Democratic People's Republic of Korea.