Bids by Japan and China for regional influence are reminders of the reason for US preeminence.
That he would spend nine days away from his domestic agenda and Washington for this four-nation tour shows just how much Asia still means to the US. The region is the most dynamic in the world, contains half of humanity, and yet it bristles with rivalry over resources, territory, and regional dominance.
Mr. Obama will need to deliver a simple message: Tensions must give way to cooperation – and the US will need to be at the table, as it has been for six decades.
As a largely benign benefactor for Asia since World War II, the US can't be excluded from most of the groupings of Asian nations. It still protects the region's sea lanes, keeps its own markets open to Asian imports, and, by its military presence, prevents any of the historic rivalry between China and Japan from erupting again.
This American task has been made easier because the US has the leading military, economy, and currency. But now, with China's Navy on the rise, the dollar slipping in value, and a recession sapping the US role as a voracious importer, the three big Asian nations – namely, China, Japan, and India – see a vacuum of power that one or all of them are trying to fill.