As a diplomatic about-turn, Washington's decision to send a US official to the talks in Geneva on Iran's nuclear programme could hardly be called earth shattering. The American representative, William Burns, is a career diplomat. He will neither participate actively in the talks (he will listen only) nor change policy (his brief is specifically to support the UN demands that Iran cease uranium enrichment as a precondition for any settlement).
But, as a gesture, it is extremely significant. Ever since Iran resumed uranium enrichment after a pause in 2002, the US has played hard cop to Europe's soft talking. The EU, France, Germany and the UK offered the inducements. Washington, led by President George Bush, kept up a steady stream of military threats.
Now, for the first time, the US is joining the soft cops. The move reflects a shift in Washington's mood that has been developing for several months. Despite all the talk of war, and Israel's increasingly vocal pressure on the US to act or let it act, the administration has been sounding an increasingly conciliatory note. This partly reflects the views of the Defence Secretary, Robert Gates, and the opposition of the generals. It could also reflect a wish to help John McCain wrongfoot Barack Obama's desire for direct talks with Iran.
But it also happens when there are indications of a change in policy on Tehran's part. Riven by internal divisions and growing public discontent at rising prices, and concern at the thought of further sanctions, Iran's leaders seem to have decided to step back from a confrontation with the West. Alongside the displays of military might and the public testing of missiles, recent statements by President Ahmadinejad and those close to the country's religious leader, Ayatollah Khamenei, have struck a less confrontational note. At the very least, they may presage a willingness to hold nuclear expansion at the current level in return for a staying of further sanctions.
All this is a long way from a settlement with Iran on its enrichment programme. And there is nothing that either the Iranians or the Americans commit themselves to which can't be reversed at the drop of a missile. But, in the meantime, both Washington and Tehran seem keen to move back from the brink. And that, at a time when all the main players – the US, Iran and Israel – have weak governments prone to desperate measures, can't be bad.