BEIJING  Secretary of Defense Robert M. Gates, on a mission to resuscitate moribund military relations with China, will not arrive in Beijing for talks with the nation’s top military leaders until Sunday. But at an airfield in Chengdu, a metropolis in the nation’s center, China’s military leaders have already rolled out a welcome for him.

It is the J-20, a radar-evading jet fighter that has the same two angled tailfins that are the trademark of the Pentagon’s own stealth fighter, the F-22 Raptor. After years of top-secret development, the jet  China’s first stealth plane  was put through what appear to be preliminary, but also very public, tests this week on the runway of the Aviation Design Institute in Chengdu, a site so open that aircraft enthusiasts often gather there to snap photos.

Some analysts say the timing is no coincidence. “This is their new policy of deterrence,” Andrei Chang, the Hong Kong editor in chief of the Canadian journal Kanwa Defense Weekly, who reported the jet’s tests, said Wednesday. “They want to show the U. S., show Mr. Gates, their muscle.”

These days, there is more muscle to show. A decade of aggressive modernization of China’s once creaky military is beginning to bear fruit, and both the Pentagon and China’s Asian neighbors are increasingly taking notice.