With the very welcome announcement by US President Barack Obama's National Security Adviser Susan Rice of separate state-visit invitations to the leaders of China and Japan, the much-discussed but so far amorphous US "pivot to Asia" policy looks to be taking on the shape of a triangle.

But triangles, a common plot device of romantic novelists, can make for stormy and unstable relationships. Japan and China both now have strong leaders. The US' conduct in Asia has not always been consistent and is sometimes indifferent. Each might wish for the US to choose between them, but with a long-abiding security treaty with Japan and economic ties to China that are historically unprecedented, they both figure America will try to play both sides of the street.

And despite the tension and everything that come with it, Chinese President Xi Jinping and Japanese Prime Minister Shinzo Abe will accept a shared relationship with Washington as preferable to any other geometry of tension and uncertainty. Two of the three triangle points are nuclear powers, and a rapid deterioration in East Asian security could produce a third all too quickly. In this regard, the triangle does appear to be a better arrangement than any other conceivable configuration.

The geopolitical expanse of the vast landmass that Asia buoyantly bodes to support more than one triangle combination. Go past China and Japan, and you run into the Republic of Korea (with which too the US has a security treaty), into Indonesia (the world's fourth-most populous country) and into India (second in terms of population but gaining on China). Rice's surprise White House "Asia pivot" announcement included news of proposed visits this year by Indonesian President Joko Widodo and ROK President Park Geun-hye as well. One also notes that all this diplomatic activity came in the wake of Obama's recent state visit to India, artfully dressed up as all bubbly and celebratory of the new government of Indian Prime Minister Narendra Modi.