Japan is calling on the Chinese government to release full and accurate details of its defence spending to reassure its neighbours about the scale of its military ambitions.
There are reports that Beijing is increasing its defence budget by nearly 11 per cent in the coming year, which would put growth in double digits for the third straight year, but analysts believe spending could be much higher.
According to figures compiled by the Stockholm International Peace Research Institute, China was the second-largest defence spender in 2011, with US$96.8 billion in expenditure announced by Beijing. Others put the figure at US$143 billion.
"China must enhance the transparency of both its defence policy and regarding its military forces," Yoshihide Suga, the chief cabinet secretary, told a press conference in Tokyo this week.
Japan - which was the world's sixth-largest investor in defence in 2011, with outlays of US$59.3 billion - worries about an increasingly aggressive China and an ongoing row over who owns the Senkaku/Diaoyu Islands.
"China's defence spending is already more than double that of Japan and, if this rate of increase continues, then by 2020, Beijing could be spending between six and nine times the amount that Japan can put into defence," Masayuki Masuda, a China analyst at the National Institute of Defence Studies, told the South China Morning Post.
A decade after that, he said, China's annual defence spending could be 12 times that of Japan. "The Chinese government always explains that its military strategy is peaceful, but without any transparency on the amounts being spent or the kinds of hardware being developed, it's impossible for anyone to verify that," he added.
With Tokyo unable to match Beijing on defence spending, Japan's tactic is to seek a "dynamic defence" to counter any thrusts at its territory, he said.
This, he said, is combined with "a regional security architecture" that builds on the long-standing defence arrangement with the United States but also builds new ties closer to home - particularly with nations that are having similar territorial disputes with Beijing, notably in the South China Sea.
The right-leaning Yomiuru newspaper weighed in on the dispute in an editorial calling on Beijing to come clean on its military capabilities and ambitions.
"China's military expansion policy ... also is a destabilising factor that could trigger military expansion in neighbouring nations, including India," it said.
Increased spending on China's navy and air force would enable Beijing to "take a more hardline stance around the Senkaku Islands," the paper stated. "Chinese vessels might seize Japanese fishing boats or apprehend their crew members."
Yomiuri said Beijing would do better to build trust with Japan by resuming talks on the creation of a system for emergency communications at sea.
The newspaper added that the Chinese government is using state power overseas to take the focus away from "disturbances that frequently erupt across that country".