To some observers, the visa row between China and the United States may appear to have erupted from nowhere. Yet it has its roots in American restrictions that have been imposed since the September 11 terrorist attacks that have severely limited the flow of business, academic and tourist travellers from the mainland to the US.
The trigger for this week's retaliatory action from Beijing was the March 22 start of fingerprinting for Chinese visa applicants, but the problem has been brewing for almost two years. Perhaps now the conflict is in the open - and now that US businesses and universities are themselves feeling the pinch from the restrictions - some solution will be found.
It is difficult to argue with the need to strengthen border controls and security measures in this age of transnational terrorism. But if the new rules severely limit the normal flow of goods, ideas and people, they need to be re-examined. The latest indication this is happening comes from US universities, which this spring saw steep declines in applications from overseas students, including those from the mainland. There are now fears that the top engineering and scientific talent that the US needs to stay competitive are going elsewhere because of the visa difficulties.
Long before this, scholars have been complaining of unnecessary delays for Chinese academics who wish to travel to the US for conferences and other programmes, while US businesses have said they face the prospect of losing their competitive edge because their customers and overseas employees have greater difficulty securing travel visas.
China is not the only country to have experienced the visa nuisance - nearly 70 countries have seen fingerprinting begin - nor will the problem be the ruin of a bilateral relationship that is increasingly friendly and co-operative. When the US doubled its application fee about this time last year, China increased its own and told Americans they could no longer apply for visas by mail. Those steps did not lead to major diplomatic friction, and neither will this latest spat.
Compared with the restrictions the US is imposing, Beijing's retaliation - cancellation of port-of-entry visas and raising the possibility of embassy interviews - is relatively mild. The broader point is the double standard the US is using for deciding which countries will experience tougher restrictions at the border.
Twenty-two European Union countries and six other first-world allies can travel to the US visa-free. They are also exempt from the inconvenience and humiliation of fingerprinting and interviews. These countries have been asked to issue passports that carry biometric information including fingerprints, but it looks increasingly likely the deadline for meeting that requirement will be pushed back several years. Meanwhile, the welcome mat for everyone else has been pulled up. Whether this broad-brush approach makes the US any safer is anyone's guess.
There is hope that the row can be settled. The major reason is the recent US decision to exempt from fingerprinting the millions of Mexicans who hold short-term visas and regularly cross the border to shop or visit family. The economic arguments and the diplomatic backlash against the plan to fingerprint all of these visitors were just too strong to resist.
In the case of the mainland, the reasons for a compromise are just as compelling. Voices from within the US are warning that their universities will suffer from constraints on recruiting from overseas. Others see unnecessary delays in doing business with China's fast-growing market. Pressure from China's diplomats may embarrass the US into looking at the issue, but self-interest will also play a role.