In the wake of China's rollout of its second stealthy-looking fighter, the J-31, earlier this week, the chief of all U.S. Air Force operations in the Pacific acknowledged that China is closing the stealth technology gap that has existed between the U.S. military and its "potential adversaries."

"They're behind us [but] they are making gains, they are improving in technology," Gen. Herbert Carlisle said today during a press conference at the Air Force Association's annual conference just outside of Washington. "We've had an advantage in stealth for a number of years. That kind of time [gap] will not occur again.... I think whatever advantages we have technologically will still be there, but they won't last as long."

Pictures emerged on Chinese military Internet forums over the weekend showing the J-31, a jet that blatantly borrows designs from the United States premier stealth fighters, the Lockheed Martin-made F-22 Raptor and F-35 Joint Strike Fighter. 

"The PRC with respect to stealth capability, they are behind us, but they will develop and they will get better, and we certainly can't rest on our position. We have to continue to get better," he added.

While this may seem obvious, it's important because U.S. defense officials have until recently downplayed China's new stealthy-looking jets (while pointing to the PRC's investment in new air defense system, ballistic and anti-satellite missiles and cyber capabilities as helping to prompt the Air Sea Battle concept and things like the Air Force's new bomber). After China unveiled its first stealthy-looking fighter, the J-20, in late 2010, then-Defense Secretary Robert Gates was quick to point out that Chinese military technology remained several decades behind that of the United States.

Still, it should be noted that simply having a stealthy shape does not mean the Chinese planes are truly stealth planes. Modern stealth aircraft involves the sues of special radar absorbent coatings, along with heat and electronic signature masking technology.

Carlisle also reiterated that the Pentagon's biggest question is what China wants to do with all of the advanced military technology that it is developing -- from aircraft carriers and stealthy fighter jets, to ballistic missiles and anti-satellite and cyber weapons.

"That's the question that we continually ask. Obviously [in the] PRC the Great Wall of China is figuratively and literally there. It's been a closed culture and a closed society. They are opening up obviously, but it's hard to get that information from them," said Carlisle. "They clearly have an approach that is more closed and more secretive than ours is, as a general rule. They have a tendency to deflect those questions with, ‘Well, what about you guys?'" 

Carlisle noted that "China considers itself a regional power and a rising world power" and that this will affect how it interacts with the United States. 

Carlisle agreed with comments made earlier in the day by Air Force Maj. Gen. Steven Kwast, director of requirements for the service's Air Combat Command, warning against a needless arms race between the United States and China. 

"That is the intent," evolving with China and other Asian nations instead of competing with them, added Carlisle. "But you generally have to do it from a position where you can continue your influence."