The recent Japanese protest that Chinese warships recently locked their weapons-control radars on to a Japanese navy destroyer and a military helicopter in two separate incidents not far from the bitterly disputed Senkaku Islands in the East China Sea raises disturbing questions.
One is the extent to which effective civilian control is being exercised over the armed forces in China. If the military, or rogue ultra-nationalist officers, call the shots in a crisis that potentially involves not just Japan but also its ally, the United States, it could trigger a wider war that would destabilise the Asia-Pacific region.
After several days of silence, China's Defence Ministry posted a denial on its website on Friday. It said that the radars on the frigates ''kept normal observation and were on alert'', but in neither case were fire-control radars used.
Japan rejected the account and said that it was considering releasing data that would prove the fire-control radar was directed at its destroyer.
Japan's Defence Minister, Itsunori Onodera, had earlier warned China it may have violated the United Nations Charter by threatening force against Japan, which administers the uninhabited Senkakus in the teeth of rival ownerships claims from China and Taiwan.
In an apparent sign of escalating militarisation in the dispute, Japanese officials say the Chinese navy's use of weapons-targeting radar was highly threatening because it could signal preparations either for a missile or shelling attack.
A Defence Ministry official in Tokyo said that in both radar incidents Japanese commanders took ''standard evasive manoeuvres'', such as changing course, but did not engage their weapons systems.
The official said the destroyer was targeted ''for several minutes'' on January 30 by a Chinese frigate about three kilometres away, while a ship-based military helicopter was locked on to 11 days earlier. The January 30 incident occurred in international waters about 100 kilometres north of the Senkakus.
Since Japan effectively nationalised the islands in September by buying several of them from a private owner, China has taken increasingly intense measures to challenge Japanese control, with jet fighters and warships replacing unarmed coast guard-type planes and vessels in several of the latest encounters.
A key question is who is authorising the Chinese build-up and actions that could lead to an exchange of fire?
Japan's Asahi newspaper reported on February 4 that China's response to the Senkaku dispute was now under the direct command and co-ordination of a top-level task force of the ruling Communist Party of China, which China's new leader Xi Jinping heads as general secretary.
It seems highly unlikely that the captains of the two frigates involved in the radar-targeting incidents would have given the orders on their own. In China's military organisation, each senior commander is flanked by a political officer to ensure that the interests of the party are acted upon.
Indeed, the CPC's 18th Congress in November that elevated Mr Xi to party chief and China's President-designate sought to tighten party (which in China means civilian) control over the armed forces. Among other things, the Congress named Mr Xi as the chairman of China's Central Military Commission. His two predecessors waited for two years for that job.
Since then, Mr Xi has visited units of all five major service branches, including the army, navy, air force, armed police and the body responsible for missiles and nuclear weapons. One theme he has emphasised is the need for the armed forces to be combat-ready.
Another theme he repeatedly underscored was the military's absolute loyalty to the CPC and its leadership. This suggests that Mr Xi and his civilian colleagues may worry about the growing political clout of the armed forces and the propensity of some nationalist hardliners to take unauthorised actions that could spark a military crisis and sabotage a negotiated settlement.
As China's defence spending has risen rapidly to become the world's second-largest (though still well behind the US), its armed forces have acquired a powerful array of weapons and equipment. These give the military a more direct interest in the conduct and enforcement of foreign and security policy, including China's sweeping claims to ownership of disputed maritime zones in the East and South China seas that the armed forces consider vital for the country's strategic interests.
Some of China's most strident hawks are serving or retired military officers. While they do not claim to speak for the leadership, they are given licence to speak out on some issues at certain times.
Air Force Colonel Dai Xu is prominent among those calling for military action to secure offshore claims. With China challenging Japan in the East China Sea, and US ally the Philippines and Vietnam in the South China Sea, he has argued that a short, decisive war, such as China's 1962 border clash with India, would return maritime territory stolen by Japan and the former colonial masters of south-east Asian countries, and deliver long-term peace.
Colonel Dai, a researcher at Beijing University's China Centre for Strategic Studies, asserts that the US would not risk war with China over these territorial disputes. ''Since we have decided that the US is bluffing in the East China Sea, we should take this opportunity to respond to these empty provocations with something real,'' he wrote in a commentary last August in the Global Times, published by the CPC's mouthpiece, the People's Daily. ''This includes Vietnam, the Philippines and Japan, who are the three running dogs of the United States in Asia,'' he wrote. ''We only need to kill one, and it will immediately bring the others to heel.''
The military hawks appear to make up only a small proportion of China's officer corps. But their influence, magnified by modern communications and social media, may be far more extensive than their numbers suggest. Their influence may also be shaping views and actions in the military command.
Just last month, another hawk, Senior Colonel Liu Mingfu, an analyst at China's National Defence University, said the US was building ''a mini-NATO'' to contain China, with the US and Japan at its core, and Australia within its orbit. He told a correspondent for Fairfax Media that his views did not represent China's policy but were consistent with what political and military leaders thought, if not what they said.
He and other hawks have been buoyed by Mr Xi's rise to the top. One of Mr Xi's new political mottoes, the ''China Dream'', echoes the title of a book by the colonel, which has had sales restrictions removed since Mr Xi emerged as leader.
The US and China's Asia-Pacific neighbours, including Australia, will be hoping Mr Xi sees that it is in China's interest to rein in the hawks, not pander to their extreme views and allow them to dictate policy.
The writer is a visiting senior research fellow at the Institute of South-East Asian Studies in Singapore.