US President Barack Obama (L) and Japanese Prime Minister Shinzo Abe speak during a bilateral press conference at the Akasaka Palace in Tokyo. (AFP Photo)
Barack Obama and Shinzo Abe were Thursday discussing the future shape of the Japan-US security alliance as they met for talks at the start of the president's tour of a tense Asia.
Both men praised the alliance, which Obama called the "foundation" of stability in the Asia-Pacific, a region where Tokyo and Beijing are facing off over territory, North Korea is threatening a nuclear test and Japan and South Korea are squabbling over history.
The "US-Japan alliance is the foundation not only for our security in the Asia-Pacific region but also for the region as a whole," the visiting US president said ahead of a formal summit.
"Our shared democratic values mean that we have to work together in multilateral settings, to deal with regional hot spots around the globe but also to try to make sure we are creating a strong set of rules that govern the international order."
The elephant in the room was China, which Japan and other Western-leaning countries say is throwing its weight around in pursuit of territorial claims in the East and South China Seas.
Along with Manila -- the fourth stop on Obama's tour -- Tokyo craves reassurance that the US is prepared to back it if push comes to shove with Beijing over their separate sovereignty rows.
Japan appeared set for a dose of soothing balm, after it was reported that the joint statement to be released after the summit will explicitly say the Senkaku Islands are covered by the agreement that obliges Washington to come to Tokyo's aid if attacked.
That would come on top of a newspaper interview Obama gave in which he said the US would oppose any "unilateral attempts to undermine Japan's administration" of the islands.
Abe is the kind of dynamic leader that Washington, frustrated by years of stagnation in Japanese politics and the economy, had longed for.
And his bid to re-cast Japan's military to enable it to take on a more equal role within the alliance -- for example by invoking the currently barred right to "collective self defence" -- was been welcomed in Washington.
"My administration intends to continue to contribute to regional peace and prosperity more pro-actively than ever," Abe said.
"At this meeting, I look forward to having exchanges with you on how the alliance should look in the future."
But Abe's nationalistic impulses and ritual offerings to a shrine that counts senior war criminals among the fallen warriors it honours bring headaches for Washington, and complicate Japan's relations with China and South Korea.
The two leaders are also under pressure to make progress on auto and agricultural market access issues blocking agreement on the wider Trans-Pacific Partnership (TPP) -- a proposed 12-nation trade bloc.
Top negotiators from both sides have spent days seeking a breakthrough over the dispute, which will entail painful political choices which could inflame anti-free trade advocates in both Japan and the United States.
Senior US officials and business figures acknowledge progress is critical to hopes of concluding the TPP, a vital prong of Obama's Asia pivot.
Soon after he arrived in Japan on Wednesday night, Obama's presidential motorcade whisked him to a tiny underground sushi restaurant, where he feasted on three-Michelin-star food with Japanese Prime Minister Shinzo Abe.
He emerged from the restaurant to declare to a crowd of journalists and well-wishers: "That's some good sushi right there".
While Obama hopes to concentrate on Asia policy on a trip partly making up for a cancelled visit to the region last year, he will find it tough to stick to his narrative as the Ukraine crisis deepens.
Washington is on the cusp of stiffening sanctions on Russia following the apparent failure of an agreement reached with Moscow in Geneva last week to de-escalate tensions in eastern Ukraine.
Time spent on the worst East-West clash since the Cold War as Obama travels through Asia would be an apt metaphor.
Obama's attention has repeatedly been wrenched away from the region by global crises elsewhere during his presidency, leading some Asian allies to question US endurance in the region.
His trip will also take him to South Korea, Malaysia and the Philippines.
Efforts to curb North Korea's nuclear ambitions will be a key topic in Seoul, and the US leader will also offer condolences for a ferry disaster feared to have killed hundreds.