But even though the sophistication of China's People's Liberation Army has exceeded US military forecasts, there is a recognition within the Pentagon that some of its most-cited conventional capabilities are still in their infancy.
China's first aircraft carrier, a refurbished Soviet-era vessel known as the Varyag bought from the Ukraine, began sea trials in July. Chinese sources said Beijing is also building two indigenous carriers, a claim the US military believes is misleading at best.
Admiral Robert Willard, commander of US forces in the Pacific, told Reuters that while China might be pursuing procurement or some other embryonic action on an indigenous carrier, it would be premature to say "a keel is laid."
"The only ship that anyone has seen and that they have discussed with any level of fidelity is the Varyag, this particular ship that has floated," Willard said in an interview.
But the refurbished Soviet-era carrier is not yet fully operational. China, the last permanent member of the U.N. Security Council to get carrier capability, will not be able to effectively field an aircraft carrier with any combat aircraft aboard for years, according to Pentagon estimates.
A Pentagon assessment to Congress noted Brazil's navy offered to provide China training in carrier operations.
"However, Brazil's limited capabilities in this area and the extensive problems with Brazil's own carrier program raise some questions as to the implications of the offer," it said.
Not ten feet tall
Then there is question of China's stealth fighter jet, the J-20, which did its first test flight during a visit by the US defense secretary to China in January.
Despite the attention given to the J-20, the Pentagon does not expect it to achieve an effective operational capability before 2018.
There are also questions about how effective its stealth capability may be. The J-20's test flight proved its stealth design but did not reveal other attributes to help it avoid detection that might come later, sources say.
"China faces several hurdles as it moves toward J-20 production, including the mastery of high performance jet engine production," the Pentagon report said.
The United States has had a proper stealth fighter since Lockheed Martin's F-117 Nighthawk made its first flight 30 years ago. That aircraft was retired from service in 2007.
Prior "low-observable" US aircraft date back to the 1950s with the U-2A high-altitude reconnaissance plane.
The PLA is also still some way from mastering the ability to mount large joint force operations, which will be needed to make the most of newfound capabilities grabbing headlines.
The US military has spent the past decade of war honing joint operations that weave together teams and skills from across its armed forces -- a hard-won but potent tool.
The US Navy's top intelligence officer warned before retiring earlier this year against overestimating Chinese military capabilities.
"I don't view them as 10 feet tall," Vice Admiral David Dorsett said. "Have we seen large joint sophisticated exercises? No ... They are at the front end of developing their military capability."
Is China "on the march"?
At the same time, the US military believes China appears on track to field a modern, regionally focused military by 2020. A comprehensive strategy to maintain the US edge in the Pacific will require investment, a tough challenge in an era of budget cuts.
The Pentagon now counts a base budget, excluding war costs, of over half a trillion dollars. China downplays its defense spending but acknowledged in March a 12.7 percent rise in 2011 defense outlays to 600 billion yuan ($94 billion).
Still, the US military, while expressing confidence in future funding for the Asia-Pacific region, is not parroting some of the more volatile China rhetoric seen in parts of Congress.
"I know some folks like to sugarcoat the terms in describing China as a rival or competitor but the fact is Communist China is an enemy of democracy," David Rivera, a lawmaker on the House of Representatives Foreign Relations Committee, said in a recent hearing on Taiwan.
The US military's estimates of China offer a more mixed view. This year's assessment noted China's lack of operational experience and large amounts of antiquated hardware but said the PLA was "steadily closing the technological gap with modern armed forces."
Dean Cheng, a China expert at the Heritage Foundation think-tank in Washington, said future Chinese advances like improvements in its anti-ship ballistic missile would influence US risk assessments when deploying near its shores.
That is not to say China will be able to flat-out deny US access to nearby waters any time soon.
"Denial is a function of risk -- what level of risk are we willing to accept in order to do whatever it is we're going to do out there," Cheng said, noting US submarines, for example, can be very difficult to detect.
The PLA's aggressive posture in the South China Sea and its increasing military edge over Taiwan are sources of concern -- as are its investments in nuclear submarines, which suggest China is seeking to support operations well beyond Taiwan.
Those concerns have found fertile ground in Congress, where the chairman of the House Intelligence Committee accused China of widespread cyber espionage.
Some lawmakers have reacted angrily to the US decision to give Taiwan a $5.85 billion arms package including upgrades to F-16 A/B fighter aircraft, instead of also delivering the late-model F-16 C/D fighters that Taipei wanted.
"China is on the march in Asia, and its primary target remains democratic Taiwan," said the House Foreign Relations Committee's chairwoman, Ileana Ros-Lehtinen.
China sees Taiwan, a self-ruled island, as an illegitimate breakaway from Beijing's rule that must accept eventual reunification.
The United States switched diplomatic ties from Taiwan to mainland China in 1979 but it is obligated by law to supply Taiwan sufficient arms for self-defense.
As China's regional military ambitions come into view, so does discussion of its global goals. But Dorsett noted China's global aspirations are longer term, seeking to turn its navy into a global power "by the middle years of this century."
"That's their timeline," said.
"Should we expect them to be much more competent 10 years from now than they are today? As long as their economy's robust, absolutely."
