US Defence Secretary Chuck Hagel moved yesterday to reassure Japan of America's commitment to its security, as Russia's annexation of Crimea raises eyebrows in a region facing its own territorial disputes with an increasingly assertive China.
The United States and its allies have made clear they have no military plans to defend Ukraine, which is not a Nato member, instead moving to isolate Russia diplomatically and impose limited sanctions. Critics say such moves are too weak to return Crimea to Ukrainian control and do little to deter further aggression.
Hagel defended the US strategy to punish Russia and told reporters ahead of two days of talks with Japanese leaders that it was natural that "allies are going to look at each other to be assured", given the crisis in Ukraine.
"It's a pretty predictable, I think, reaction not just of nations of this area, of this region, but all over the world. It has to concern nations," he said.
But Hagel rejected any suggestion of weakness as he renewed US commitments to Japan, which is locked in a dispute with China over islands in the East China Sea.
Washington takes no position on the sovereignty of the islands, called the Senkaku by Japan and the Diaoyu by China, but recognises that Japan administers them and says they fall under the US-Japan Security Treaty, which obligates America to come to Japan's defence.
Addressing US and Japanese forces at Yokota Air Base, Hagel said one of the goals of his trip to the region was to assure allies of America's commitment to "our treaty obligations". "We're serious about that," he said.
Daniel Russel, President Barack Obama's diplomatic point man for East Asia, said on Thursday that the prospect of economic retaliation should discourage Beijing from using force to pursue territorial claims in Asia, in the way Russia has in Crimea. He stressed that China also should not doubt the US commitment to defend its Asian allies.
It is unclear if US reassurances can on their own allay worries in Japan that Washington might one day be unable or unwilling to militarily defend the country, despite Obama's strategic "pivot" towards the Asia-Pacific region.
Obama is expected to visit Japan later this month.
Such fears have added momentum to Japanese Prime Minister Shinzo Abe's drive to beef up Japan's forces while loosening constitutional limits on military actions overseas.
His government this week unveiled an overhaul of a decades-old ban on weapons exports.
Last October, the US and Japan agreed to broad plans to expand their defence alliance, including plans to position a second early warning radar there by the end of this year. There is already one in northern Japan and the second one would be designed to provide better missile defence coverage in the event of a North Korean attack.
The US will also begin sending long-range Global Hawk surveillance drones to Japan this month for rotational deployments, and they are intended to help step up surveillance around the Daiyou islands, a source of heated debate between Japan, and China which both claim the remote territories.
In an interview published before his arrival, Hagel said he welcomed the possibility of Japan giving its military a greater role by allowing it to come to the aid of allies under attack.
"We welcome Japan's efforts to play a more proactive role in the alliance, including by re-examining the interpretation of its constitution relating to the right of collective self-defence" Hagel told the Nikkei, Japan's main financial newspaper.
Hagel, who travels next to China after his weekend visit to Japan, just wrapped up three days of talks with Southeast Asian defence ministers in Hawaii, where he warned of growing US concern about territorial disputes in the South China Sea.
"We have differences [with China]. And the only way to deal with differences is [to be] straight up honest, talk about it and deal with it," Hagel said.
Russia's annexation of Crimea came up in discussions at the talks, one senior US defence official acknowledged.
But the defence official played down the extent of discussions, saying there "wasn't a lot of hand wringing".
Additional reporting by Associated Press