China firmly upholds her sovereignty and maritime rights and interests in the South China Sea. [Photo/Xinhua]

In October, the US guided missile destroyer USS Lassen conducted a "freedom of navigation" operation within 12 nautical miles of China's Meiji and Zhubi reefs.

In December, a United States Air Force B-52 bomber "accidentally" flew within 2 nautical miles of China's Huayang Reef.

On Saturday, the Pentagon announced an "innocent passage" by the guided-missile destroyer USS Curtis Wilbur within 12 nautical miles of China's Zhongjian Island.

On the surface, these are "routine" operations US Senator John McCain says are "normal occurrences" China will have to accept.

Yet this is not a Tom-and-Jerry kind of game where no party gets seriously hurt.

There is real potential danger, because the US challenges to China in the South China Sea are showing a trajectory of escalation.

Zhongjian Island is part of the Xisha Archipelago, where there is no current, active dispute, and hardly part of the issue of the day.

The Pentagon did display some diplomatic sophistication this time, claiming that the USS Curtis Wilbur "challenged attempts by the three claimants－China, Taiwan and Vietnam－to restrict navigation rights and freedoms around the features they claim by policies that require prior permission or notification of transit within territorial seas".

Ignoring the fact this violates the US' recognition of "one China", reaffirmed by US Secretary of State John Kerry on Wednesday, the Pentagon's statement raises legitimate suspicions that it has an agenda to further complicate the South China Sea issue.

As in the rest of the South China Sea, there is no evidence the named "claimants" are attempting to "restrict navigation rights and freedoms". Enlarging the South China Sea issue by extending it to the Xisha Archipelago may be an attempt to drive a wedge between the mainland and Taiwan by dragging the latter into a long dormant and increasingly forgotten "dispute".

The US wants a larger role in the Asia-Pacific. And it is bent on preempting a perceived Chinese challenge.

There is no better way to do this than by making things messier, to make itself "needed" and "wanted".

What China needs and wants is peace, but as the Chinese saying goes, while the tree craves calm, the wind will not abate. Beijing needs to react accordingly, and prepare for all possibilities.

However, the country learned the significance of comprehensive national strength the hard way. It should not be distracted. It should rise above stress responses and stay focused on its development agenda.