One moment Japan was planning to join the Asian Infrastructure Investment Bank (AIIB); the next we heard talk of Japan's 'caution' about the move. Its unsettling attitude is actually a bargaining chip with the US.

Ultimately, together with the US, Japan stuck to its bottom line and did not join the AIIB. Abe said that Japan was in no hurry to join the AIIB, intending to show the US that Japan is a 'reliable' ally.

It has been only five months since China announced the establishment of the AIIB, and many US allies have already signed up. Abe's "fidelity" may comfort Obama for the time being, but he also knows that in the end Abe will throw in his hand and join the AIIB. Abe's visit to the US is aimed at persuading the US to agree to end the ban on collective self-defense and help Japan out with its problems surrounding Asia, war, and history.

But for Obama, the bigger prize would be the successful negotiation of the Trans-Pacific Partnership Agreement (TPP) - a key step in his Asia 're-balancing strategy'. And whether Japan joins the AIIB or not is key to the successful negotiation of TPP. TPP is also influenced by the trade promotion authority (TPA); if TPA is not passed by Congress, Obama's "return to the Asia-Pacific" strategy will begin to unravel.

There is still a question mark over whether Japan and US will stick together or go separately in the future. But the fact that the business community of Japan is lobbying to join the AIIB shows that the alliance between the US and Japan may not stand the test of time. The state of the relationship will be much clearer by the end of June this year — either the two countries will reach agreement on the TPP, or they will work together to deal with China and the AIIB, or Japan will join the AIIB and a new world economic structure will be formed. 

This article is edited and translated from 《奥巴马会怎样看待安倍的“忠心”》，source: The Beijing News, author: Chen Bing