Challenges mount for Obama's administration in East Asia

While the US administration is making diplomatic progress on some of the Middle East's thorniest security issues, problems are piling up in Asia, a region where President Barack Obama had hoped to play a bigger part in American foreign policy.

Despite efforts to forge deeper ties with China to make East Asia more stable, Beijing's declaration of a maritime air defence zone has escalated its territorial dispute with US ally Japan. The US responded by flying B-52 bombers through the zone on a training mission Tuesday without informing Beijing.

Analysts say the risk of a military clash between the Asian powers has increased - a serious concern for the US because its treaty obligations mean it could be drawn in to help Japan.

Meanwhile, relations between America's core allies in the region, Japan and South Korea, have deteriorated. South Korea is bitter over Japan's attitude towards its colonial past and wants more contrition from Tokyo for Japan's use of Korean sex slaves in the second world war.

That complicates the strategic picture for the Obama administration as it looks to advance its work in Asia and strengthen not just its own alliances, but get its partners in the region to collaborate more.

Vice-President Joe Biden will broach these issues when he travels to Japan, China and South Korea next week - a trip to demonstrate that the top level of the administration remains focused on Asia.