China's growing military capabilities are raising concerns in the United States and among its neighbors.
The U.S. Department of Defense says China is developing a ballistic missile that can hit aircraft carriers more than 1,500 kilometers away.
That program is in addition to the country's already extensive missile defense system, which includes more than one thousand missiles pointed at Taiwan, which Beijing considers part of its territory.
In addition, the Pentagon says China is working to build its first aircraft carrier, which would put it in a small group of nations able to project power well into international waters.
Need for a deterrent
While Chinese government officials say little about defense plans, some Asia security experts think there are two major reasons for its missile and carrier programs.
One is Taiwan - which has been separately governed since Nationalist forces fled there in 1949, after losing the country's civil war. China has threatened to use force to regain control if Taiwan declares independence. The United States has said it will help the island defend itself from an attack.
Wu Xinbo is an international relations professor at Shanghai's Fudan University.
Wu says if there were a military conflict in the Taiwan Strait, China needs a deterrent to prevent a U.S. aircraft carrier from entering the area to, in his words, "interfere with the Chinese handling of the situation."
Wu says China wants to build an aircraft carrier largely to defend international shipping lanes, which Beijing considers crucial to its export-driven economy.
Denny Roy is a senior fellow at the East-West Center in Hawaii. He says he is not surprised that the Chinese would develop a long-range ballistic missile to protect what it considers its interests.
"The Chinese have long had particular expertise in missile development, so it is natural that they would rely on this as a way of countering U.S. strength. It is much easier for the Chinese to build an anti-aircraft carrier missile than building an aircraft carrier battle group." Roy said.
China ramping up investment in nuclear weapons
China was ramping up investment in nuclear weapons, long-range missiles, submarines, aircraft carriers and cyber warfare, and building up a force that could strike as far as the US territory of Guam.
The U.S. and other countries have questioned Beijing's need for either a carrier or new missiles because, they say, there currently are no real threats to China's interests. But Wu says there is also one basic reason for doing so now - money.
Wu says it was not possible for China to build an aircraft carrier before, but now China's economic boom has given the country the means to work on one.
James Nolt is a senior fellow who specializes in U.S.-East Asia relations at the World Policy Institute in New York. Since 2007, he has lived in Nanjing, China, as the head of the New York Institute of Technology's Nanjing campus.
Nolt says even if China builds its own aircraft carrier, it will be decades behind the United States in operational know-how and in numbers.
"The ability to develop an effective carrier, it involves a lot of technology and a lot of training, and operational capabilities, that it might take China many years to develop," Nolt says, "if they chose to do so. Even if they had an aircraft carrier, one aircraft carrier would not be significant."
Nolt points out that even with its missile programs and plans for a carrier, China's military capabilities lag behind those of the United States. "They talk about China without comparing it to the U.S. in any systematic way, which if they did, it would be very easy to see that China's power is vastly smaller in many areas and its capabilities are vastly limited compared to the U.S.," he said.
But China's neighbors, including Southeast Asian nations that dispute Beijing's claims to scores of small, uninhabited islands in the South China Sea, have quietly expressed concern about its military buildup.
Pentagon report rejected
U.S. officials say they do not know the extent of China's military power. They repeatedly have called for greater Chinese transparency on its military capabilities and intentions.
The East-West Center's Roy says China may want to preserve some secrecy because it sees itself as the weaker power.
"China, seeing itself as being much inferior to the U.S. military at the moment, believes that it's quite unreasonable for the United States to ask for a large degree of transparency in Chinese military development, because from the Chinese point of view, they need to hide their weaknesses from the United States," Roy said.
Beijing rejected the latest Pentagon report and says it exaggerates what it calls "China's normal national defense and military build-up." The Defense Ministry has given no specific information about its progress in building a missile that can strike aircraft carriers.
Shortly after the Pentagon report was released, though, a leading Chinese newspaper, The Global Times, published an editorial calling on China to have an anti-ship ballistic missile and other so-called "carrier-killing measures." The editorial said China must build what it described as "a credible deterrence" to counter U.S. naval power in the Pacific Ocean.
At the same time, Beijing has grown increasingly vocal in recent months in demanding that U.S. ships stay away from wide areas of ocean - covering much of the Yellow, East and South China seas - where it claims sovereignty.
