China has urged the United States not to flex its muscles in the Asia-Pacific, saying it is not conducive to regional peace and stability.

The remarks, made by the Ministry of National Defense on Tuesday, were in response to the US Navy's deployment of two aircraft carriers and their accompanying ships in the Philippine Sea on Saturday.

The message was unmistakable, and the timing was deliberate, a US official familiar with the planning of the operation, who spoke on condition of anonymity, was quoted by The New York Times as saying.

"It could have been conducted later," the official said.

Admiral John Richardson, the chief of US Naval Operations, was quoted by Reuters as saying: "It's a signal to everyone in the region that we're committed, we are going to be there for our allies."

The Chinese Defense Ministry said that the US' military alliances are "a reflection of a Cold War mentality".

"Drawing in a country outside to interfere in regional affairs will only further destroy regional peace and stability," the ministry said.

The deployment of the two carriers－John C. Stennis and Ronald Reagan－comes at a time when the results of the arbitration case unilaterally launched by the Philippines in 2013 are expected.

Niu Jun, a professor of international relations at Peking University, said the US is attempting to exert pressure on China's activities in the South China Sea.

Fan Jishe, a researcher of US strategies at the Chinese Academy of Social Sciences, concurred.

The deployment shows that the US fears its presence in the West Pacific might be challenged, and is also intended to demonstrate the credibility of its security commitment to its allies, Fan said.

But Washington's show of strength will only sharpen the situation in the region, Fan added.