Concern is rising over the growing crisis in the East China Sea and the possibility of a major escalation in the row between China and Japan over the disputed Diaoyu/Senkaku Islands.
Experts warn that the situation is fragile and "extremely dangerous" following China's declaration of an Air Defence Identification Zone requiring all aircraft flying near the islands to file flights plans, maintain two-way radio communications and "respond in a timely and accurate manner" to identification inquiries.
The United States has already tested China's resolve and its promise to adopt defensive emergency measures if aircraft did not comply by flying two B-52 bombers through the zone. Further tests will come with an exercise in the area by Japanese warships and the carrier USS George Washington. The US has reaffirmed that its defence treaty with Japan includes any potential conflict in the East China Sea.
China has deployed its sole carrier, Liaoning. It also has Russian Su-30 fighters within range of the islands.
Beijing did not react to the B-52s beyond noting the "provocation", but had earlier warned: "If an aircraft doesn't supply its flight plan, China's armed forces will adopt emergency defensive measures in response."
Australia, bound to Japan through the US alliance and a supporter of Prime Minister Shinzo Abe's ambitions to dump constitutional limits restricting its large armed forces to national self-defence, has now been drawn into the crisis. The Government had already irritated China by declaring Japan Australia's "best friend in Asia" and increasing military co-operation with the US. Foreign Minister Julia Bishop further angered Beijing by declaring the new zone an "unhelpful" move that would not contribute to regional stability. China, Australia's biggest trading partner and key underwriter of the mining boom, said Bishop's "irresponsible" statements could not be accepted and demanded Canberra "immediately correct its mistake". Immediately at stake are the long-running negotiations for a free trade agreement.
Australian National University Professor Gavan McCormack said responsible thinking by all parties was needed "to prevent the unthinkable happening", although it was difficult to see a path forward given the nationalistic emotions involved. "This is an uncompromising quality that makes the whole thing so dangerous."
He added: "When the US sends in B-52 bombers ... into the recently claimed air defence zone, that's serious ... The addition of aircraft to the equation has been an extremely dangerous development."
ANU Professor Hugh White told ABC radio the crisis was "really about China's bid to assert its power in Asia and America's attempt to restrict that". He added: "So this really does go to the sort of whole future of Asia and if it's not well managed it can lead to really serious escalating rivalries and eventually conceivably to conflict, so how it's managed is extraordinarily important."
Analysts also believe the crisis may be a tit-for-tat retaliation in response to increasing militarism and nationalism in Japan, and Tokyo's recent moves to assert sovereignty over the disputed islands. The tiny barren chain is surrounded by rich fishing grounds and potentially rich mineral reserves, but is caught in overlapping claims that for decades were set aside by both countries.