For a trading route that went into decline more than 500 years ago, the Silk Road is remarkably popular these days. The term crops up in headlines about the rise of China, the development of Central Asia and the UAE's links with the rest of Asia. The phrase Silk Road certainly adds much-needed spice to the bland lexicon of economists who prefer to talk of "developing south-south trade".
Recently, however, the term has found another, more sinister usage. It has become diplomatic shorthand for a US exit strategy from Afghanistan.
In this sense, the "New Silk Route" is being promoted in Washington as a replacement for the failed US policy of turning Afghanistan into a flourishing democracy by force of arms.
The plan now is to transform Afghanistan from a blank spot on the world's trading map to a "crossroads of economic opportunities going north and south and east and west", in the words of Hillary Clinton, the US secretary of state.
Economic ties will become the universal solvent of hostilities among Afghanistan's neighbours, which all have their own proxies inside the country.
The plan has several advantages in Washington: it is a free-market vision, based on the ideas of opening up trade, reducing border restrictions and unleashing the commercial talents of the people of the region to spread prosperity. Afghanistan's mineral wealth would be the catalyst.
For the US Treasury, the great advantage is that it would cost American taxpayers very little at a time of rising government debt. This cut-price dream is touted as a replacement for the gritty reality of Afghanistan, where the rulers siphon millions of dollars abroad as they hide behind blast walls in the capital, Kabul, until it is time to flee.
America, of course, is the land of optimism and will always rush to replace failure with an inspiring vision.
It is indeed good psychology not to dwell on failure, but we should always be wary of fleeing from reality into the arms of an enticing grand scheme. The current state of the euro, the European common currency, is a lesson in where a lack of scepticism will lead.
There are many reasons why this new emperor has no clothes. The original Silk Road trading network fell into disuse because it was more reliable to transport goods by sea than to brave the unstable political currents of the land route.
Things are somewhat better these days. Kazakhstan, for example, is a good example of a stable country which looks both north to Russia and east to China and is intent on building durable links. But the rest of the region is characterised more by distrust among neighbours than by amity.
The second reason to doubt the Silk Road is that it is seen as an American plan that Washington does not have the right to implement, barring some miraculous transformation of Afghanistan over the next two years. Russia is keen to preserve its interests in Central Asia, and China has its own ideas of how to fit Afghanistan's mineral wealth into its development plans.
Anthony Cordesman, a defence expert at the Centre for Strategic and International Studies in Washington, is leading the charge against the New Silk Road plan, suggesting its proponents are more interested in "political cover for a rapid exit than a credible approach to reducing the problems of transition".
Mr Cordesman adds: "Even extremely favourable assumptions indicate the 'New Silk Road' has no practical prospect of dealing with the near- and perhaps mid-term problems of transition."
Apart from the excess of optimism, there is one glaring hole in this diplomatic ship: Iran, which by any standards was a key part of the original Silk Road and has to be part of any regional settlement for Afghanistan, is generally passed over in silence.
But Iran is a key neighbour of Afghanistan, with strong cultural and linguistic ties. It has its own proxies who can help to tip the country into deeper instability, or act as a useful counterweight to the power of the Taliban. It provides shelter for more than one million Afghans, and would have to accommodate more if the situation gets worse, a risk that the US does not face.
Any attempt to get the regional powers around a table must include Iran, if only to defuse the damage it can do if left outside. But Iran and the US have, since the 1979 Islamic Revolution, been locked in permanent hostility, with the US and its allies now trying to strangle Iran with sanctions.
It is no easy task to transform Iran from international pariah to positive contributor to a regional settlement for Afghanistan. Is it even possible? We do not know, but the effort is a necessary precondition for regional peace after the US exit.
This is one of the reasons why talks, held in Baghdad this week, on Iran's nuclear programme are so important.
There is no expectation of an instant resolution of suspicions, always denied by Iran, that it is creating the capability to make a nuclear weapon. But if these talks or later ones could produce a broad dialogue between Iran and its interlocutors - the five permanent members of the UN Security Council and Germany - it would be significant progress.
One of the issues for discussion should be a settlement for Afghanistan, and if it is going to work this should not be a US-led process, but one which springs from the interests of the regional powers.
Any progress here would be baby steps - uncontroversial issues such as trade, water resources or emergency responses to earthquakes. None of this is going to set pulses racing in Washington think tanks or yield a compelling headline.
But if the US really wants a regional solution, the regional states all have to get on board the same bus. They do not have to agree on everything, but they need to see engagement as in their interest. Now that is a real diplomatic challenge.
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