|Ever since 1945, the US has regarded itself as the leader of the "free world". But the Obama administration is facing an unexpected and unwelcome development in global politics. Four of the biggest and most strategically important democracies in the developing world - Brazil, India, South Africa and Turkey - are increasingly at odds with American foreign policy. Rather than siding with the US on the big international issues, they are just as likely to line up with authoritarian powers such as China and Iran.
The US has been slow to pick up on this development, perhaps because it seems so surprising and unnatural. Most Americans assume that fellow democracies will share their values and opinions on international affairs. During the last presidential election campaign, John McCain, the Republican candidate, called for the formation of a global alliance of democracies to push back against authoritarian powers. Some of President Barack Obama's senior advisers have also written enthusiastically about an international league of democracies.
But the assumption that the world's democracies will naturally stick together is proving unfounded. The latest example came during the Copenhagen climate summit. On the last day of the talks, the Americans tried to fix up one-to-one meetings between Mr Obama and the leaders of South Africa, Brazil and India - but failed each time. The Indians even said that their prime minister, Manmohan Singh, had already left for the airport.
So Mr Obama must have felt something of a chump when he arrived for a last-minute meeting with Wen Jiabao, the Chinese prime minister, only to find him already deep in negotiations with the leaders of none other than Brazil, South Africa and India. Symbolically, the leaders had to squeeze up to make space for the American president around the table.
There was more than symbolism at work. In Copenhagen, Brazil, South Africa and India decided that their status as developing nations was more important than their status as democracies. Like the Chinese, they argued that it is fundamentally unjust to cap the greenhouse gas emissions of poor countries at a lower level than the emissions of the US or the European Union; all the more so since the industrialised west is responsible for the great bulk of the carbon dioxide already in the atmosphere.
Revealingly, both Brazilian and Chinese leaders have made the same pointed joke - likening the US to a rich man who, after gorging himself at a banquet, then invites the neighbours in for coffee and asks them to split the bill.
If climate change were an isolated example, it might be dismissed as an important but anomalous issue that is almost designed to split countries along rich-poor lines. But, in fact, if you look at Brazil, South Africa, India and Turkey - the four most important democracies in Latin America, Africa, Asia and the greater Middle East - it is clear that none of them can be counted as a reliable ally of the US, or of a broader "community of democracies".
In the past year, President Luiz Inácio Lula da Silva of Brazil has cut a lucrative oil deal with China, spoken warmly of Hugo Chávez, president of Venezuela, and congratulated Mahmoud Ahmadi-Nejad on his "victory" in the Iranian presidential election, while welcoming him on a state visit to Brazil.
During a two-year stint on the United Nations Security Council from 2006, the South Africans routinely joined China and Russia in blocking resolutions on human rights and protecting authoritarian regimes such as Zimbabwe, Uzbekistan and Iran.
Turkey, once regarded as a crucial American ally in the cold war and then trumpeted as the only example of a secular, pro-western, Muslim democracy, is also no longer a reliable partner for the west. Ever since the US-led invasion of Iraq, opinion polls there have shown very high levels of anti-Americanism. The mildly Islamist AKP government has engaged with America's regional enemies - including Hamas, Hizbollah and Iran - and alarmed the Americans by taking an increasingly hostile attitude to Israel.
India's leaders do seem to cherish the idea that they have a "special relationship" with the US. But even the Indians regularly line up against the Americans on a range of international issues, from climate change to the Doha round of trade negotiations and the pursuit of sanctions against Iran or Burma.
So what is going on? The answer is that Brazil, South Africa, Turkey and India are all countries whose identities as democracies are now being balanced - or even trumped - by their identities as developing nations that are not part of the white, rich, western world. All four countries have ruling parties that see themselves as champions of social justice at home and a more equitable global order overseas. Brazil's Workers' party, India's Congress party, Turkey's AKP and South Africa's African National Congress have all adapted to globalisation - but they all retain traces of the old suspicions of global capitalism and of the US.
Mr Obama is seen as a huge improvement on George W. Bush - but he is still an American president. As emerging global powers and developing nations, Brazil, India, South Africa and Turkey may often feel they have more in common with a rising China than with the democratic US.
The Financial Times