If there were a prize for the world's sulkiest state, it would surely go to Russia.
Enter the Kremlin, and you get an overwhelming sense of a great power that has been deeply offended.
Tense relations: "We always try to smile at one another"
"We always try to smile at one another," President Vladimir Putin's foreign policy adviser Sergei Prikhodko says wearily when I ask about the atmosphere at recent Russian-American summits.
"But we've asked many questions, and we haven't got answers."
He is talking about the deepening chill in East-West relations over the last year, a chill some see as the prelude to a new Cold War.
The Kremlin has a simple explanation: America, it believes, has never given up its ambition to contain Russia. And the eastward expansion of the Nato alliance is designed to achieve that.
But Washington dismisses those claims as mere bluster, aimed at reasserting Russian control of an Eastern European empire it lost with the fall of the Soviet Union.
What the two sides agree on is that a real opportunity for East-West stability has been lost since President Putin and his opposite number George W Bush came to power at the beginning of the new millennium.
"When we were in a very shabby condition in the early to mid-1990s, all our Western friends were telling us we want Russia to become strong," Russian foreign minister Sergei Lavrov remembers.
He believes Western leaders should have been pleased when the increasingly weak Boris Yeltsin was replaced in 2000 by a new president, Vladimir Putin, whose chief promise was to restore Russia's strength.
Certainly, they were intrigued.
The then British prime minister Tony Blair took up an invitation to visit Mr Putin in his home town of St Petersburg even before he was elected.
"What we did know was that Russia had emerged from a terrible period in its history, and there were opportunities for engagement that wouldn't come round again," says David Miliband, now Foreign Secretary, who accompanied Mr Blair on the trip as a junior official.
The best opportunity for engagement between Russia and the West came a year later, when Mr Putin was the first foreign leader to ring President Bush after the tragedy of the 9/11 attacks.
What the Russian president proposed, in effect, was a joint war on terrorism.
Overthrowing all previous tenets of Kremlin foreign policy, Mr Putin invited America into what was historically Russia's own backyard - Central Asia - to establish the bases it would need to fight the Taleban in Afghanistan.
No quid pro quo was discussed. But the Kremlin certainly hoped that America would now see Mr Putin's much-criticised war in Chechnya as part of the global fight against terror, and that the geo-political rivalry that began with the expansion of Nato in the 1990s might come to an end.
It didn't happen. "We expected a lot more... co-operation, not competition for influence in Central Asia and other regions," Sergei Prikhodko says.
Indeed, Russia believes the competition for influence became more intense after 9/11.
In 2004, Nato expanded again to include seven more countries, three of them - the Baltic states - formerly part of the Soviet Union itself.
And at the end of that year, the Kremlin watched, humiliated, as one of its closest and most strategically important allies, Ukraine, was convulsed by a pro-democracy revolution that Russia believed was inspired from the West.
In response, Mr Putin's anti-Western rhetoric has grown ever louder.
In 2007, in a speech in Munich, he accused the US of "overstepping its national borders in every way".
And this month, he said Russia was being forced to retaliate against a "new arms race unfolding in the world".
At the state department in Washington, Assistant Secretary of State Daniel Fried refuses to accept the Kremlin's concerns about Nato.
"Russia's Western borders are the most secure, the most benign, from Russia's point of view, in history," he says.
And Nato's Secretary-General, Jaap de Hoop Scheffer, takes the same line: "Newly admitted Nato members are not building up their armies. They are modernising their armies, they are making them expeditionary."
Mr de Hoop Scheffer believes Russia's complaints are rhetoric for rhetoric's sake.
Certainly, the Kremlin's charges against the West seem to have become particularly frequent during the current Russian election season.
And for all Mr Putin's talk of "huge" plans for a new generation of nuclear weapons, his military budget is still 25 times less than that of the United States.
But that does not mean the West should not worry. It needs Russia's help to solve a huge range of global problems - from Kosovo to Iran and from terrorism to global warming.
And gradually, that help is becoming less forthcoming.
In the Czech Republic, on the front line of the new East-West confrontation, shadow foreign minister Lubomir Zaoralek is glad to have his country now protected by Nato.
But he thinks the West should take the Kremlin's sensitivities seriously.
"Russia is not so strong to be a real enemy for us," he says. "But we can make it an enemy. It is our decision."
Tim Whewell's series of four documentaries, The Kremlin and the World, is now running on the BBC World Service. The first programme can be listened to on the BBC World Service website. Programmes two to four air on Wednesday 20, Monday 25 and Wednesday 27 February.