CHEBARKUL, Russia (Reuters) -- President Vladimir Putin said on Friday security threats had forced Russia to revive the Soviet-era practice of sending bomber aircraft on regular patrols beyond its borders.

A Russian strategic bomber flies over an airfield outside Moscow during an air show.

Putin said 14 strategic bombers had taken off simultaneously from airfields across Russia in the early hours of Friday on long-range missions.

"We have decided to restore flights by Russian strategic aviation on a permanent basis," Putin told reporters after inspecting joint military exercises with China and four Central Asian states in Russia's Ural mountains.

"Today, August 17 at 00:00 hours, 14 strategic bombers took to the air from seven airfields across the country, along with support and refueling aircraft ... From today such patrols will be carried out on a regular basis.

"We hope our partners will treat this with understanding."

At U.S. President George W. Bush's Texas ranch, White House spokesman Gordon Johndroe said he did not believe the flights posed a threat to the United States.

"Militaries around the world engage in a variety of activities, so this is not entirely surprising," he said.

But the sorties are likely to add to Western concern about Russia's growing assertiveness. That trend has prompted some U.S. policymakers to draw parallels with the Cold War.

Don't Miss Russia resumes nuke bomber sorties

Putin caused a stir this year by saying Russian missiles would once again be aimed at targets in Europe if Washington persisted with plans to build a missile defense shield in eastern Europe.

Russian diplomats have clashed with the United States and European governments on issues such as Kosovo, energy, and Moscow's treatment of its ex-Soviet neighbors.

Western military leaders have said this year that Russian flights near their airspace were becoming more frequent after a long quiet period.

One Western defense official called the flights "a little bit of chest-pounding, trying to let people know Russia is back in the game".

Putin said that when Russia had cut its flights in 1992, other military powers had not reciprocated.

"Flights by other countries' strategic aircraft continue and this creates certain problems for ensuring the security of the Russian Federation," Putin said.

That appeared to be a swipe at the U.S. and NATO, whose strategic bombers have continued to fly long-range missions.

As Putin spoke to reporters and television cameras, four Russian military helicopters appeared and hovered in the background while Russian tanks trundled behind him, even though the exercises had ended long before.

During the Cold War, Russian long-range bombers, which can carry strategic nuclear weapons, played elaborate games of cat-and-mouse with Western air forces.

Earlier this month Russian air force generals said bomber crews had flown near the Pacific island of Guam, where the U.S. military has a base, and "exchanged smiles" with U.S. pilots scrambled to track them.

The Pentagon said the Russian aircraft had not come close enough to U.S. ships to prompt American aircraft to react.

In July, two Russian Tu-95 "Bear" bombers made unusually long sorties over the North Sea, leading Norway and Britain to scramble fighter jets to follow them. Russia's air force said later it was a routine flight. E-mail to a friend

Copyright 2007 Reuters. All rights reserved.This material may not be published, broadcast, rewritten, or redistributed.