If China were a contestant in an online game — such as, say, World of Warcraft — it would probably be accused of trolling, the internet term for committing gratuitous mischief for the sheer delight of getting a rise out of others.

But as this is the real world, with the possibility of real war, we should probably rule out a playful adolescent urge as China's motive for its surprise declaration of an Air Defence Identification Zone for much of the East China Sea.

Apart from being one of the world's busiest transportation corridors, this zone also includes that grouping of hotly contested rocky islets known in China as the Diaoyu and in Japan as the Senkaku islands.

Once famous for providing albatross feathers to the world's milliners, the uninhabited islands are claimed by both countries.

But more recently, since the discovery of oil and gas deposits nearby and China's dramatic economic transformation, they have become the flashpoint for the mutual ill-feeling that dates back to Japan's wartime occupation of China and beyond.

The declaration of an ADIZ means that China now requires any aircraft entering the air space over a vast area of the East China Sea, including the disputed islands, to identify itself, report a flight plan and follow air traffic control instructions.

Japan immediately denounced the declaration as a "dangerous escalation," in the tensions between the two countries, while U.S. Defence Secretary Chuck Hagel called it a "destabilizing attempt to alter the status quo in the region."

American B-52s, as well as Japanese, Taiwanese and South Korean military planes have all flown through the zone since Beijing's declaration two weeks ago to demonstrate that they will not comply with China's conditions.

For its part, China says it sent up fighter jets to "counter any provocative actions from Japan."

Should we be worried?

So far, this has all been shadow boxing, rather than confrontation. The different fleets of military jets seem to have been flying in different areas at different times to make a point, rather than start a war.

Commercial flights are not greatly affected. They routinely communicate with Chinese air traffic control anyway, and most countries, including the U.S., have recommended that their airlines obey the new rules.

China's and Japan's air defence zones. (Reuters)

China's official news agency, Xinhua, reported that 55 airlines from 19 countries have followed the new procedures in the days since the announcement. Japan, however, has told its airlines not to comply.

China points out that it has every right to establish an identification zone like this to match those of many other countries, including Japan, which has had one since the 1950s, extending it as recently as 2010.

Even Canada has an ADIZ, established jointly with the U.S. during the Cold War.

Since these zones are the air space over international waters surrounding a country, they are not sovereign territory. The established practice is to locate military intruders and escort them until they leave.

Canada, for example, scrambled CF-18 fighters to see off a couple of Russian bombers in 2008.

China itself considered declaring such a zone as a security measure in the run-up to the 2008 Olympics, but decided not to, presumably because it would have disturbed the international charm offensive that was in full swing at the time.

The drumbeat of nationalism

But if China is clearly within its rights in asserting that national security requires greater supervision of approaching aircraft, the announcement nevertheless came as a shock because there was no prior consultation with its neighbours.

Also because the declared zone overlaps pre-existing ones set up years ago under U.S. guidance by Japan, South Korea and Taiwan.

And since the slightest move by any of the countries in this conflict-prone region always causes an uproar, China is disingenuous in asserting it is merely doing what others do.

Anticipating international criticism, government spokesman Hong Lei even had a proverb ready in advance.

"Their logic is simple," he said of China's critics. "They can do it while China cannot, which could be described with a Chinese saying, 'the magistrates are free to burn down houses while the common people are forbidden even to light lamps.'"

It's not entirely clear why China decided that this was the right time (just in advance of a long-scheduled visit by U.S. Vice-President Joe Biden) to stir up a long-standing dispute that had settled down somewhat since its eruption in the summer of 2012.

Domestic politics are certainly a factor, in both Beijing and Tokyo.

In his first year as China's top leader, President Xi Jinping has a firmer grip on all the levers of power, including the military, than any predecessor since Deng Xiaoping.

U.S. Vice-President Joe Biden met with Japanese Prime Minister Shinzo Abe before moving on to China this week. A much more informal get together, though the new air defence zone dominated the discussion, and Japan's lower house voted to condemn the new Chinese move shortly after Biden left. (Associated Press)

The so-called Chinese Dream, which has emerged as the key concept for his decade in office, includes a return to what he considers the country's rightful pre-eminence in the region, and a vision of China as a great power to equal, or maybe even surpass, the U.S.

Across the East China Sea in Japan, newly empowered Prime Minister Abe Shinzo is similarly pursuing a more nationalistic future for his country, which has not gone unnoticed in Beijing.

China accuses Abe of having plans beyond the self-defence policy that has underpinned Japan's military thinking since its defeat in 1945, and perhaps even of abandoning its taboo on nuclear weapons.

An editorial in the official English language China Daily said earlier this week: "If the U.S. is truly committed to lowering tensions in the region, it must first stop acquiescing to Tokyo's dangerous brinkmanship. It must stop emboldening belligerent Japanese Prime Minister Shinzo Abe to constantly push the envelope of Japan's encroachments and provocations."

For their part, American military strategists believe that China's strategy is to try to undermine American influence in East Asia by gradually pushing U.S. naval might back out into the Pacific, away from the "near sea" to the "second island chain."

From that perspective, the ADIZ can be seen as just one in a series of small moves to extend China's reach.

'Two centuries of humiliation'

Today, nationalism is a powerful force in China as it seeks to emerge from what Communist Party propaganda calls "two centuries of humiliation."

And the Communist Party has been increasingly turning to nationalism as an antidote for the growing public scorn it faces for its recent history of corruption and decadence.

Seen in that light, risky confrontations with foreign powers can be a good thing in the party's eyes, so long as China does not suffer a loss.

But a reminder of where the danger lies came this week with the deployment of new American patrol aircraft in Japan.

The earlier version of this plane, which carried out surveillance missions over Chinese waters for decades, collided with a hot-dogging Chinese jet tracking it in 2001, setting off one of the most serious crises between Beijing and Washington since diplomatic relations were restored in 1971.

The danger today is not that China, Japan, or the U.S. wants to start a war in these waters, it is that another such incident could easily lead to uncontrolled escalation.