MOSCOW - The Moscow Machine-Building Enterprise Salyut on the east side of town has put up a massive Soviet-style poster advertising its need for skilled workers. The New Year's party at the Chernyshev plant in a northwest suburb featured ballet dancers twirling on the stage of its Soviet-era Palace of Culture.

The reason for the economic and seasonal cheer is that these factories produce fighter-jet engines for a wealthy and voracious customer: China. After years of trying, Chinese engineers still can't make a reliable engine for a military plane.

The country's demands for weapons systems go much further. Chinese officials last month told Russian Defense Minister Anatoly E. Serdyukov that they may resume buying major Russian weapons systems after a several-year break. On their wish list are the Su-35 fighter, for a planned Chinese aircraft carrier; IL-476 military transport planes; IL-478 air refueling tankers and the S-400 air defense system, according to Russian news reports and weapons experts.

This persistent dependence on Russian arms suppliers demonstrates a central truth about the Chinese military: The bluster about the emergence of a superpower is undermined by national defense industries that can't produce what China needs. Although the United States is making changes in response to China's growing military power, experts and officials believe it will be years, if not decades, before China will be able to produce a much-feared ballistic missile capable of striking a warship or overcome weaknesses that keep it from projecting power far from its shores.

"They've made remarkable progress in the development of their arms industry, but this progress shouldn't be overstated," said Vasily Kashin, a Beijing-based expert on China's defense industry. "They have a long tradition of overestimating their capabilities."

Ruslan Pukhov, the director of the Center for Analysis of Strategic Technologies and an adviser to Russia's ministry of defense, predicted that China would need a decade to perfect a jet engine, among other key weapons technologies. "China is still dependent on us and will stay that way for some time to come," he said.

Indeed, China has ordered scores of engines from the Salyut and Chernyshev factories for three of its new fighters - the J11B, a Chinese knock-off of the Russian Su-27; the J10, which China is believed to have developed with Israeli help; and the FC1, which China modeled on an aborted Soviet design. It also told Russia that it wants a third engine from another factory for the Su-35.

How China's military is modernizing is important for the United States and the world. Apart from the conflict with radical Islamism, the United States views China's growing military strength as the most serious potential threat to U.S. interests around the world.

Speaking in 2009, Liang Guanglie, China's minister of defense, laid out a hugely ambitious plan to modernize the People's Liberation Army, committing China to forging a navy that would push past the islands that ring China's coasts, an air force capable of "a combination of offensive and defensive operations," and rocket forces of both "nuclear and conventional striking power."

The Pentagon, in a report to Congress this year, said that that the pace and scale of China's military reform "are broad and sweeping." But, the report noted, "the PLA remains untested in modern combat," thus making transformation difficult to assess.

'Could be sitting ducks'



One area in which China is thought to have made the greatest advances is in its submarines, part of what is now the largest fleet of naval vessels in Asia. In October 2006, a Chinese Song-class diesel-powered attack submarine reportedly shadowed the USS Kitty Hawk aircraft carrier and surfaced undetected four miles from the ship. Although the Pentagon never confirmed the report, it sparked concern that China could threaten the carriers that are at the heart of the U.S. Navy's ability to project power.

China tried to buy Russian nuclear submarines but was rebuffed, so it launched a program to make its own. Over the past two years, it has deployed at least one of a new type of nuclear-powered ballistic-missile submarine called the Jin class and it may deploy as many as five more.