The largest Chinese arms production companies, all state-owned, declined interview requests. Their finances are opaque, though there are some statistics on their Web sites and in the state news media.

The China North Industries Group Corporation, or the Norinco Group, said on its Web site that its profits in 2012 were 9.81 billion renminbi, or about $1.6 billion, a 45 percent increase from 2010. Its revenues in 2012 were 361.6 billion renminbi, or about $59 billion, a 53 percent increase over 2010. Another company, the China South Industries Group Corporation, or CSGC, said on its Web site that it had profits of about $1 billion in 2011, on revenue of about $45 billion, both big increases over 2008.

China’s investment has been heaviest in fighter planes — both traditional and stealth versions — as well as in jet engines, an area in which China had until now been dependent on Western and Russian partners, said Guy Anderson, a senior military industry analyst in London with IHS Jane’s.

“China has been throwing billions and billions of dollars at research and development,” he said. “They also have a strategy of using the gains they get from foreign partnerships to benefit their industrial sector. So they should not have any trouble catching up with their Western competitors over the medium term, and certainly over the long term.”

He estimated that China was still a decade away from competing head-to-head with Western nations on the technology itself. But Chinese equipment is priced lower and could become popular in emerging markets, including in African and Latin American nations.

“We are in an era of ‘good enough’ — the 90 percent solution that will do the job at the best possible price,” Mr. Anderson said. “In some cases, that may even mean buying commercial equipment, upgrading it slightly and painting it khaki.”

New customers for Chinese equipment include Argentina, which in 2011 signed a deal with the Chinese company Avicopter to build Z-11 light helicopters under license. Mass production for the Argentine military began this year, and 40 helicopters are expected to be built over the next several years. The value of the contract has not been made public.