MOSCOW — President Vladimir Putin promised Saturday to re-equip the Russian air force with hundreds of new aircraft as part of an ambitious military modernization program.

Speaking at an airshow at Zhukovsky just outside Moscow marking the air force's 100th anniversary, Putin said the military will receive more than 600 new combat planes and 1,000 helicopters by 2020.

He said boosting the air force is a key priority for the government. "I'm sure, each of us will feel pride for the country, for the people who build such aircraft and pilot them," he said.

Russia's defense spending has fallen sharply since the 1991 Soviet collapse, leaving the air force to rely on aging Soviet-built planes and depriving pilots of the opportunity of regular training flights.

"I want to thank those who helped our air force survive during a difficult period in the 1990s and the early 2000s, and remained loyal to their jobs and traditions in the years when the planes were grounded," Putin said during a meeting with military pilots and air force veterans.

A recent boom in oil revenues has allowed the Kremlin to launch a costly effort to upgrade military arsenals. Air force chief Gen. Viktor Bondarev said on Ekho Moskvy radio that the military will get 180 new aircraft this year alone.

Putin, who has sought to revive Russia's Soviet-era clout during his 12 years in power, has overseen a military buildup that comes amid a strain in relations with Washington over NATO's U.S.-led missile defense plans that the Kremlin sees as a threat to Russia's security.

Russia's leaders have said they plan to spend a total of 20 trillion rubles (about $625 billion or euro510 billion) on new weapons by 2020.

But despite a hike in defense spending, Russia's military industries, weakened by years of post-Soviet industrial meltdown, have struggled to meet rising orders for new weapons and to develop new designs. Analysts say that most of Russia's new weapons systems are refurbished versions of Soviet-era designs. They blame corruption, aging equipment and broken links between subcontractors.

The development of Russia's first stealth fighter, intended to match the U.S. F-22 Raptor, has dragged on slowly. The Sukhoi T-50 made its maiden flight in January 2010, about two decades after the Raptor, which it closely resembles. The new Russian fighter still lacks new engines and state-of-the art equipment, and its serial production is only expected to begin in 2015 at the most optimistic forecast.

Russian aircraft-makers also have been slow to develop modern drones, prompting the government to buy some from Israel.