From the ground it looked an impossible manoeuvre. The Russian Sukhoi-35 shot vertically into the sky before flipping forward in midair. It then raced downwards with an ear-ripping roar.

The crowds were impressed. Even the seasoned US pilots standing on the tarmac next to their grey-painted B-52 bomber looked on admiringly. Nearby an array of lethal Russian missiles had been laid out.

Next to them Russian pilots chatted under the shade of a formidably armed MiG.

The Maks-2007 international airshow near Moscow was the biggest in Russia's post-Soviet history and an apparent symbol of Russia's resurgent military might.

Last week, President Vladimir Putin announced that Russia's ageing fleet of strategic bombers had resumed "combat missions". On Tuesday, the MoD said the RAF had sent out two Typhoon fighters after spotting a Tupolev-95 bomber heading towards British airspace.

The encounter seemed to symbolise Russia's renewed military threat and follows a tumultuous eight months in which a hawkish Mr Putin has denounced US power, torn up a conventional arms agreement with Nato, grabbed a symbolic chunk of the Arctic, and accused Britain of "stupidity" in its handling of the Alexander Litvinenko murder.

And yet defence experts were yesterday dismissive of Russian strength, branding its air force a "Potemkin village".

Since the collapse of the Soviet Union, Russia has been forced to slash defence spending, leaving an ill-equipped conscript army to fight in Chechnya.

The army's tanks are old; Russia's ships and submarines have seen better days; the navy's much-vaunted sea-launched Bulava missile still doesn't seem to work, despite a decade of development.

"In terms of military threat they are a joke," Robert Hewson, the editor of Jane's Air-Launched Weapons, said, assessing the array of Sukhoi and MiG fighters on display at the airshow, held at the former Soviet Zhukovsky air base.

 "Everything is a relic from the Soviet era. The level of technology you see in the UK, Sweden and the US is much higher.

"The Russians are very good at radar.

They understand missiles and aerodynamic design.

They are terrific engineers.

But since the end of the cold war their military has got worse."

The Russian tabloid Trud-7 came to the same conclusion on Thursday, describing the state of Russia's armed forces as "lamentable". Pronouncements that Russia had got back its old Soviet military glory were mere "armour rattling" it said.

The state of Russia's air force is indicative. It has gone an entire decade without a single new plane.

Its military aviation industry fared better than its civilian manufacturers, mainly due to large orders from China and India.

Until recently the air force could not afford its own products. Its bombers were almost all built decades ago, although it has 60 to 80 Tu-90 "Bear bombers" built in the 90s.

Few experts believe the Bears could ever penetrate British defences. "[The Bear bomber] can carry a load of cruise missiles.

But it sticks out like a sore thumb on the radar. It's slow and cumbersome," Douglas Barrie, of Aviation Week, said.

"What has been portrayed as a return to strategic operations is really sabre-rattling of the most laughable cold war kind. Before Russia returns to Soviet military levels you are looking at a decade-plus of sustained, high-level military investment."

It seems clear Mr Putin is determined to restore Russia's status as a global power.

Earlier this year Mr Ivanov Russia's first deputy prime minister, the man most likely to succeed Mr Putin announced a £97bn revamp of the armed forces.

From now until 2015, Moscow plans to modernise and exceed the Red Army in "combat readiness", he said. Russia's current defence budget is £16bn, almost four times the 2001 figure, all paid for by soaring oil and gas revenues.

Russia held wargames last week in the Urals involving troops from Russia and China and four central Asian states. Moscow has infuriated Georgia after a Russian missile landed on the outskirts of its capital, Tbilisi.

Much of the military posturing is for internal consumption, ahead of parliamentary elections in December and a presidential poll in spring. Pictures showing a shirtless Mr Putin on a fishing trip have been a source of national pride.

The US appears relaxed about this newfound Russian machismo. After all, Washington's defence budget is at least 20 times bigger than Moscow's. And US generals are unperturbed by the Russian Bears close to its airspace.

Brigadier-General Richard Sherlock, director of international security operations, was asked at a Pentagon briefing on Thursday about Russian flights close to Guam and Alaska.

US planes had been scrambled, but he played down the significance: "Militaries all over the world conduct a variety of operations.

This is not something new."

Sean McCormack, the US state department spokesman, said last week: "If Russia feels as though they want to take some of these old aircraft out of mothballs and get them flying again, that's their decision."

Anatol Lieven, a Russia specialist at the Washington-based New America Foundation, said it was clear Moscow was going to ramp up its response to President George Bush's controversial missile defence project in eastern Europe.

"It indicates to the US that this move is not cost-free and shows the Russian population that the government is still acting toughly to defend Russian prestige abroad," he said. "It is depressing but it is not a new cold war."