The Associated Press reports:

At a once-secret airfield outside Moscow, test pilot Sergei Bogdan proudly introduces reporters to what was billed as the latest in Russian military aircraft technology, the Su-35 fighter-jet.

But the plane is only an upgrade of a 20-year-old model - and it can't match the speed and stealth of the U.S. F-22 Raptor, which entered service in 2005.

Former President Vladimir V. Putin, now Russia's powerful prime minister, has boasted of new weapons systems and of strengthening the armed forces, raising fears in the West of a Cold War-style military buildup. Flush with oil money, the Kremlin is in the market for new weapons.

But Russia's state-run defense industries, experts say, face a crumbling manufacturing base and pervasive corruption; they have produced little advanced armament in the Putin era.

The Victory Day parade in Red Square in May was intended to showcase the nation's military might. Instead, Russia's arsenal showed its age. Most of the planes, tanks and missiles that rolled past Lenin's Tomb dated to the 1980s or were slightly modernized versions of decades-old equipment.

Bogdan, affectionately patting his Su-35 in a hangar at the Zhukovsky Flight Test Center outside Moscow, hailed its agility, advanced electronics and new engines: "It's very light on controls and accelerates really well."

But Alexander Golts, an independent defense analyst, said the Su-35 is an example of how Russia's weapons industries are taking old designs out of mothballs and trying to sell them as new.

"The Soviet Union saw a tide of new weapons designs in the late 1980s which didn't reach a production stage," he said. "They can be described as new only in a sense that they weren't built in numbers."

Russian officials have spent two decades trying to build a so-called fifth-generation fighter equivalent to the Raptor, but the plane still has not made its maiden flight - and analysts are skeptical that the first test flights will take place next year as promised.

The director of the Sukhoi aircraft-maker, which is developing the new fighter, admitted that the company has a long way to go. But he said the pace of construction could accelerate soon.

"I don't think that we are lagging behind in a critical way," Mikhail Pogosyan said.

As work to build the new plane drags on, another major weapons program also faces hurdles. The new Bulava intercontinental ballistic missile, designed for use on nuclear submarines, has failed repeatedly in tests. Prospects for its deployment look dim.

"The loss of technologies and the brain drain have led to a steady degradation of military industries," said Alexander Khramchikhin, an analyst with the Institute for Political and Military Analysis.

Russia's economic meltdown after the collapse of the Soviet Union put many subcontractors out of business, rupturing long-established production links. Assembly plants were left to rely on limited stocks of Soviet-built components or forced to try to crank up their own production.

"Now, when we finally get state orders, plants often can't fulfill them due to the lack of components," Valery Voskoboinikov, a government official in charge of aviation industries at Russia's Ministry of Industry, testified recently at parliamentary hearings.

Despite Putin's pledges to modernize arsenals, during his eight years as president the military bought only a handful of new combat jets and tanks.

Russian arms sales have grown steadily in recent years, reaching a post-Soviet record of more than $7billion last year, according to official statistics. Russia accounted for a quarter of global arms sales in 2003-2007, a close second after the United States, according to the latest report by the Stockholm International Peace Research Institute.

But Russia has suffered several recent, highly publicized failures in arms exports, in which the broken subcontractor chain and swelling production costs were widely seen as key factors.

Russia recently failed to fulfill China's order for 38 Il-76 transport planes and Il-78 tankers, leading to the suspension of the deal. Earlier this year, Algeria returned MiG-29 fighter planes it bought from Russia, complaining of poor quality.

"The system has been broken all the way down," said Anatoly Sitnov, who oversees the aviation industries in the Chamber of Commerce and Industry.

Russia's aging work force presents another challenge. Many highly skilled workers left defense industries in the 1990s for higher-paying jobs in the private sector, and the arms industry's meager wages have hampered the recruitment of younger workers.

The average age of Russia's aircraft industry workers is now 45, and that figure keeps rising. "There is an acute shortage of key specialists: turners, welders, millers," Voskoboinikov said.

Obsolete equipment has hurt efficiency. The last major modernization of defense plants occurred in the early 1980s, and many machine tools used in these factories are even older.

The government has responded by creating huge state-controlled military conglomerates, saying they will streamline manufacturing. Critics say they will stifle competition, encourage corruption and further weaken Russia's arms industry.

"We built good planes in the past because we had a competition between aircraft makers," Svetlana Savitskaya, a Soviet cosmonaut who is now a lawmaker, said during parliamentary hearings.

"Pulling all of them together under one roof will end competition and destroy what we had," she said. "But it could make it more convenient for some to steal government funds."