China sidestepped calls for action after two unarmed American bombers flew over the East China Sea in defiance of its new air defence identification rules.
But some analysts say Beijing may be forced to respond if this happens again.
Japan's two biggest airlines on Wedneday also said they would stop providing flight plans required of planes passing through China's newly declared Air Defence Identification Zone (ADIZ).
Beijing has warned of "defensive emergency measures" if aircraft do not comply with the rules for its air defence zone.
The Defence Ministry, which did not refer to these measures yesterday, said it had monitored the bombers' flight and insisted that China had "the ability to effectively manage and control" the airspace.
The ADIZ announcement last Saturday drew strong criticism from Japan and the United States, and also concern from countries such as Australia.
China's reaction to the US bombers disappointed some Chinese. Still, analysts warned that further attempts by Washington or Tokyo to challenge Beijing in the ADIZ could push the Chinese to take more muscular action.
China's new rules require foreign aircraft to supply a flight plan, clearly identify their nationality and maintain radio contact with the Chinese authorities.
But on Tuesday, a pair of B-52 bombers flew over disputed islands claimed by Japan and China in the East China Sea, underlining the US' assertions that it will not comply with Chinese demands.
This was followed by Japan's two main carriers - All Nippon Airways and Japan Airlines - which passed through the area yesterday without notifying China, following the Japanese instructions to stop giving flight plans.
International relations scholar Li Mingjiang said Beijing is under pressure to prove it is serious about enforcing the zone.
"With reports that the US and Japan have ignored China, it looks like the air defence zone is essentially a set of rules on paper only," he said.
China faces the choice of "either swallowing the bitter fruit of 'saying something and not meaning it', or it must show force to prove it is serious", said Beijing- based security analyst Wang Xiangsu. This is "dangerous for regional security".
Foreign Ministry spokesman Qin Gang said on Wednesday that China's reaction to foreign aircraft in the zone would depend on "how big the threat" was.
At a conference call in Washington on US Vice-President Joe Biden's visit to Asia next week, administration officials said the visit creates an opportunity to meet directly with policymakers in Beijing to convey concerns and seek clarity on Chinese intentions.
Mr Biden will also convey the message that the US has a "rock solid commitment" to its allies and wants to see an easing of tensions in the region, officials said.
Additional reporting by Jeremy Au Yong
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