To the consternation of America, which sees itself as guaranteeing the current security order in East Asia, the new leaders of the region’s two biggest powers are moving further and faster with agendas that unsettle the status quo.



One is the son of a People’s Liberation Army general in China’s revolutionary era who later became a staunch supporter of economic opening (Xi Zhingxun). The other is the grandson of the bureaucrat who pioneered East Asia’s “development model” in occupied Manchuria (Nobusuke Kishi, later prime minister) and son of a man who was preparing to be a kamikaze pilot when World War II ended (Shintaro Abe, later foreign minister).



Since becoming China’s communist party chief and state president in November 2012, when he was expected to focus on economic reform, Xi Jinping has taken an unexpected close handling of the vast People’s Liberation Army as chairman of the party’s Central Military Commission, a role assumed more diffidently by his predecessor.



His leadership has been marked by a readiness to up the ante in the campaign to wrest the uninhabited Senkaku (in Japanese) or Diaoyu (in Chinese) islands in the East China Sea from Japanese control, and to push China’s claims to resources in a vast scoop of the South China Sea.



In November, China declared an “air defence identification zone” covering the Senkaku/Diaoyu group and partly overlaying the aviation identification zones of Japan and South Korea, warning of possibly “defensive” measures against aircraft that did not report. In January, its authorities issued a note requiring foreign vessels to obtain licences for fishing in waters administered by Hainan, the island province jutting into the South China Sea. It is not yet clear what these waters are, but they could be those enclosed by the famous “nine-dash line” marking China’s claims on its official maps.



Meanwhile, Japan’s prime minister, Shinzo Abe, celebrated the first anniversary of his return to office on 26 December, by making a formal visit to the Yasukuni shrine. The site has been shrouded in controversy since 1977 when its priests included 14 wartime leaders convicted of war crimes among the Japanese war dead it venerates.



This follows a year in which Abe signalled he wanted to revamp the landmark apology in 1995 by then prime minister Tomiichi Murayama expressing “heartfelt apology” and “deep remorse” for Japan’s “aggression” before the 1945 surrender. Abe said he wanted a more “forward-looking” statement, and quibbled at the word “aggression”. He has also condemned the Tokyo tribunal in which the 14 war leaders were convicted as “victor’s justice”, and said they were not guilty of anything under Japanese law.



The Yasukuni visit took international relations experts by surprise. They expected it much later in Abe’s term. The US Government expressed its “disappointment” in an unusual open criticism.



“I do not believe the visit helped American foreign policy,” noted Kurt Campbell, who was assistant secretary of state for East Asia in President Barack Obama’s first term, in a talk at Washington’s Centre for Strategic and International Studies (CSIS). “It puts us in a very difficult position.”



Washington officials are dismayed that Abe is stirring up historical grievances not just with China but with its other regional ally South Korea, at a time when they want international pressure on Beijing to moderate its assertive approach to its maritime claims.



Although a new National Security doctrine published by Tokyo in December emphasises a tighter defence relationship with the United States, Abe’s wartime revisionism and his professed wish to amend the war-renouncing Article 9 of the postwar constitution could also indicate a yearning to break free of the American embrace.



China’s “assertiveness” can be seen partly as reaction to measures provoked by Japanese ultra-nationalist groups to plant the flag on the disputed islands, or to fishing and petroleum activity by other claimants in the South China Sea.



But it is also seen as testing Washington’s willingness to back up the strategic “pivot” or “rebalancing” to Asia announced by Obama in Canberra in November 2011 – an incremental policy of converting maritime resource zones into virtual territory by excluding military and spying activity, and as pushing the US Navy back from China’s sea approaches.



The question being asked, said former Bush administration national security official Michael Green at the CSIS talk is: “Does the United States really have the juice if things get rough in the East China Sea?”



That fits into a narrative that Obama’s Asia pivot has dissipated somewhat, with his second-term secretary of state, John Kerry, concentrating on the Middle East. Washington’s prompt dispatch of two B-52 bombers on an unannounced flight through China’s new air defence identification zone, and Kerry’s swing through East Asia has not entirely dispelled the sense of distraction.



Few expect a deliberate military move on the islands by China, though Japan is gearing up a new marine corps and thinking of new naval assets to deal with a lodgement. But Campbell and others see a high risk of an accidental clash, as emphasised by a near collision between US and Chinese warships in the South China Sea in December.



Campbell said Washington has “tried for two decades” to set rules of engagement at sea. He thinks China’s reluctance comes from an unwillingness to reveal limits of capability, from tensions between the party and the PLA, from a worry about conceding US forces rights to operate up to its 12-mile territorial limit, and from strategic use of “uncertainty” as a deterrent.



Further tension can be expected mid-year, when benign weather allows young nationalists from Japan, China, Taiwan and Hong Kong to show their stuff in rented fishing boats. Meanwhile, the princely scions of two Asian dynasties may further push agendas that in different ways challenge the post-1945 American order - to the dismay of those who think correcting domestic economic and social imbalances the better way to strength.



Hamish McDonald, a fellow at the Australian National University’s College of Asia and the Pacific, is in Washington as a public policy scholar at the Woodrow Wilson Centre.