HOW HE WILL REASSURE HIS COUNTRY'S allies without leaving the impression the United States and its allies are ganging up on China will be a test of US President Barack Obama's political acumen as he starts a four-nation visit to the Asia-Pacific in Japan on Wednesday.

This will be a difficult balancing act, as he has to sustain the US' image as a credible ally, while at the same time not fueling speculation that Washington is dedicated to containing China, an allegation the White House has vehemently denied.

Despite the same old reassurances being repeated time and again by officials from both the White House and the Pentagon, the leaders of Japan and the Philippines want desperately to hear it from the lips of the US commander-in-chief, because they want a shot in the arm to give them the bravado to continue messing with China.

Washington meanwhile wants to keep its dogs at heel, as undisguised support for troublemakers on China's doorsteps would severely undermine the US' moral authority and could drag the country into an unwanted conflict with China.

What messages the US president conveys on this trip will hopefully display the forethought and foresight necessary, because both the Asia-Pacific and US "pivot" to the region stand at a critical crossroads. What we hear in the next week or so will in part determine the future orientation of Sino-US relations.

If President Obama is truly striving for a healthy relationship conducive to his country's long-term benefits, he must give assurances to his nation's allies while preventing his trip being hijacked by them and becoming a farce of China-bashing.

Even if geopolitical self-interest and ignorance about Asian history, as well as his government's "no bias" stance, keep him from drawing fair conclusions over the territorial disputes in the region, Obama should be able to tell who is pushing the envelope these days and escalating tensions here.

The Shinzo Abe administration has on multiple occasions displayed its desire to whitewash Japan's war crimes, overthrow international judicial verdicts, and revise the country's pacifist Constitution. The collective pilgrimage by 146 Japanese parliament members to the notorious Yasukuni Shrine on Tuesday, along with Abe's sending of an offering, is a defiant show of their disregard for the increasing concerns of the international community that the country is becoming a loose cannon.

If Obama wants to maintain peace in the region and prevent his country from being dragged into unwanted scenario by an untrue and unruly ally, he must tighten the leash on both Japan and the Philippines.