As I fly into Tbilisi, memories flood back from my first visit to Georgia in 2005. I remember the infectious energy of President Mikhail Saakashvili and his fellow Rose Revolutionaries who had overthrown the government of Eduard Shevardnadze. It felt as if Ocean's Eleven had been given custody of the republic; a cabal of beautiful young people dashing around changing the country from top to bottom. In his first few months, Saakashvili sacked 14,000 corrupt traffic cops, abolished 80 per cent of government regulations and extracted unpaid tax from dozens of former officials. I flew around with him in a helicopter opening schools and sports centres in provincial villages, basking in the admiration of grateful citizens.

Now there is no exuberance. With Russian tanks stationed just 30 minutes from the capital, flying in helicopters is dangerous. Saakashvili damaged his reputation as a democrat last year with a crackdown on opposition rallies, but his decision to go to war was even more catastrophic. Vladimir Putin had tried everything from trade blockades and energy cut-offs to pogroms against Georgian migrants to destabilise the young pretender.

It was Saakashvili's own instincts that set him up for the Russian trap in August. Like his political heroes Mustafa Kemal Atatürk, David Ben-Gurion and Charles de Gaulle, he wanted to build a nation in his image, bringing Georgia's secessionist regions back into the fold. In June, Ron Asmus of the German Marshall Fund of the United States and I wrote an article warning that we were "sleepwalking into a war in Georgia". Everyone on the ground knew that Abkhazia and South Ossetia were on the edge; that Russia was trying to provoke a war; and that Saakashvili would rather fall into one than lose the breakaway provinces. But the US and the EU, which had missed an opportunity to send monitors to Georgia in 2005, failed to lay down clear red lines to Moscow or Tbilisi. Thanks to French diplomacy, the fighting stopped, and Saakashvili has set about rebuilding the country with his customary energy. But the peace is not stable while the EU remains divided about how to respond to Moscow's expansionism.

I leave Georgia for New York. George Soros has invited me for dinner in his Central Park apartment, to speak at a fundraiser for the Central European University. Soros has had an incredible year. He helped launch Barack Obama's campaign for the presidency with an early donation; put forward a plan to deal with the financial crisis that many say was Gordon Brown's inspiration; and he has a ringside seat on events in Georgia (Putin still blames the Soros Foundation in Tbilisi for causing the coloured revolutions in Georgia and Ukraine). But it was Soros's account of western mistakes in the 1990s that I found most compelling. He described with feeling how the west threw away the chance to turn Russia into an open society in 1991. As part of a narrative of missed opportunities, Soros told a story about asking the White House to back a new Marshall Plan. He was told by Robert Zoellick - then an official on the National Security Council - that the US couldn't help at that stage because Russia still had "bad" policies on Cuba. By the time western governments woke up to the scale of the challenge it was too late. The result was Russia's collapse and humiliation, and the emergence of Putin's energy empire.

The next morning I join the hordes of European diplomats descending on Washington. The gift shop in Union Station is ready to cater for their Obamania: packed with Obama T-shirts, keyrings and dolls ("action figures you can believe in"). But Obama's people are not playing ball - he has forbidden anyone involved in the transition from talking to foreigners, so even my old friends on his team are cagey about meeting up.

His loyal camp has yet another reason to be nervous: the naming of Hillary Clinton as secretary of state. They thought they were in line for the best jobs, but now have to look on as Clintonistas are floated for key posts.

But, for all the excitement in the US capital, the most important event of my week is one I can only attend vicariously. My wife and I are expecting our first child in January, and every Thursday we trek to Hendon for antenatal classes with a Jewish matriarch who has had as many children as we've had hot meals. Because I'm in Washington I have to make do with a telephone report from my wife. She tells me about breathing exercises and labour positions, but then moves on to the important stuff. Do you think, she asks, that we can show our baby that he is the centre of our universe? As she talks I cannot help feeling thrilled to be alive; to be married to the most wonderful woman in the world; and to be expecting a baby in the New Year. I grasp for Obama's magical words: "Yes we can! Yes we can!"

Mark Leonard is executive director of the European Council on Foreign Relations and author of "What Does China Think?" (Fourth Estate, £8.99)