Visiting United States Vice- President Joe Biden sought to ease tensions with China by not confronting his hosts in public over the new air defence zone, but highlighting instead both countries' effort to build "a new model" of collaboration.
But experts said Mr Biden was likely to have pressed China's leaders not to implement its contentious Air Defence Identification Zone (ADIZ) during their closed- door meetings, which went on well beyond schedule.
In Mr Biden's meetings with President Xi Jinping and Vice- President Li Yuanchao, both sides discussed ways to advance bilateral ties under the "new model of major-country relations" espoused by Mr Xi and embraced by US President Barack Obama during their summit in California in June.
The closest reference to China's ADIZ was when Mr Xi cited how "regional hot-spot issues keep cropping up", as a reason why strengthening cooperation and dialogue "is the only right choice facing both our countries".
The unexpected silence came a day after Mr Biden and Japanese Prime Minister Shinzo Abe, at their joint press conference in Tokyo, strongly criticised China for unilaterally changing the status quo in the East China Sea by launching the ADIZ on Nov 23.
China wants aircraft, before they fly through its first-ever ADIZ, to comply with self-identification rules or face "defensive emergency response".