The US on Saturday sent one of its naval vessels within 12 nautical miles of the Xisha Islands in the South China Sea. The move, according to the Pentagon, was about "challenging excessive maritime claims that restrict the rights and freedoms of the United States and others." The Chinese side criticized the behavior of a "serious political and military provocation."

Until recently, China-US frictions have been fixed on the Nansha Islands. The latest intrusion by US vessels is a high-profile US provocation that has expanded to the Xisha Islands. Xisha is under China's actual control and China has released the territorial sea baseline of the Xisha Islands, including Zhongjian Island. Therefore, the US provocation this time is more vicious.

Currently, China and the US have been focused on making their own moves in the South China Sea disputes. China is building islands in accordance with the law, and the US cannot prevent China from doing so despite strong protests. The US sent warships to provoke, and China protests against it strongly, yet with few effective countermeasures.

It is hard to evaluate the strategic nature of Sino-US confrontations in the South China Sea. China seems to have more room to maneuver, while the US apparently has more control over the overall situation.

Since it happens at the door of China, China feels that the US is circling to contain it and the US vigilance against China is aggressive. There is a long way to go before China can have an equal footing with the US. Such equality can only be achieved with the build-up of strategic strength.

China's military strength still significantly lags behind that of the US. If the US is ready for a face-off in the South China Sea, it can quickly gather its military strength despite the far distance.

We also face similar setbacks in the East China Sea. We bear enormous pressure from Washington in our peripheral areas, and the relative backwardness of China's military might is the weakest link in our competition with the US. Chinese people must be clear about the broader strategic significance of this reality.

The US provocation comes ahead of the 2016 two sessions which are scheduled in March. This reminds us that we must retain a high growth rate of military spending in spite of the economic downward trend.

The defense expenditure of a big power must constitute a certain percentage of its overall expense. China's military budget only takes up 2 percent of its GDP, much lower than the US figure of 4 percent. Before we reach the same ratio as the US, we should hold a cautious attitude toward decreasing the defense budget.

China needs to accelerate its speed of building up strategic strike capabilities, including a nuclear second-strike capability. The US provocation will not stop due to Chinese objections. In the short-term future, we will have limited means to counter the US.

It will probably take China a dozen years or longer of military build-up before it faces a different situation in the South China Sea.