[Gordon] Brown devoted only a few sentences to Iran and they were sober ones, shorn of all rhetoric. Nevertheless, they did manage to contain the three strands of current thinking on how to deal with Tehran and its nuclear ambitions, artfully keeping each option - carrots, sticks and sharper sticks - in play.
Initially, he established that there is indeed a problem to solve. In defiance of those who insist there is no evidence that Iran wants anything more than a civil nuclear capability - a view well represented in the blogosphere, not least among commenters on the Guardian website - Brown drew attention to the fact that Iranian nuclear activity had been "hidden from the world" for many years. It is this record of evasion, "of lying and cheating to the International Atomic Energy Agency", according to Charles Grant of the Centre for European Reform, that has persuaded many otherwise doveish European governments that Tehran is up to something. Grant cites secret nuclear facilities in Iran whose existence was only admitted once dissident groups had revealed them.
That is not the only source of suspicion. Those watching are also puzzled as to why the Iranians had documents showing how to cast uranium in hemispheres, a step only required for making warheads. They also ask why, if civil nuclear power is all the Iranians want, they don't simply import enriched uranium from abroad.
These signals, and several others, have persuaded governments - and not only those in Washington and Jerusalem - that, even if there is not definitive, fizzing-fuse proof of an Iranian bomb, this is the direction in which the Iranians are heading.
Why is that a problem? Israelis would offer an existential answer - "Because an Iranian nuke would wipe us off the map" - but Europeans have a different reply. They fear a nuclear Tehran would trigger a nuclear arms race in the Middle East, the most volatile region in the world. Even if you accept that Iran has more justification than most for wanting a deterrent, sandwiched between US forces in both Iraq and Afghanistan and with nuclear Pakistan next door, the danger of proliferation is a real one. Already, several Arab states are showing a sudden interest in "civil nuclear" programmes - rather puzzling given their abundance of oil - stirred into action by the mere prospect of an Iranian bomb. It is worth noting that, even though they have been convinced for 40 years that Israel is a nuclear power, Egypt or Saudi Arabia never showed the interest in nukes they're showing now.
Unless Iran manages to allay some of these fears in reports due imminently from the EU's Javier Solana and from the IAEA, then the debate will remain fixed not on whether there is a problem, but on solutions. Start with the scariest: military action. Brown was careful not to rule it out - indeed, he even hinted at it: "Iran should be in no doubt about our seriousness of purpose." But is it really possible?
No one, not even the wildest neocon crazy, is imagining an Iraq-style invasion: America is too stretched, if nothing else. But a series of air strikes on selected targets, as in 1998's Desert Fox assault on Iraq, is at least under discussion. I'm told that American military planners have drafted fairly detailed sketches of just such an operation. The leading presidential candidates have all stressed that they will not tolerate a nuclear Iran. One US commentator wrote recently that George Bush and Dick Cheney do not look like men about to leave office without getting this done. In this version, Bush believes - incredibly - that the best way to safeguard his legacy is by sorting out Iran before he goes. And Cheney wouldn't trust some future Democrat to do it.
But the plain fact is that Bush lacks the political strength, especially in Congress, to act. Those same military planners are counselling against it, while it's widely believed that Bush's defence secretary, Robert Gates, would quit rather than attack Iran. The reasons are obvious: Iran would hit back, through its militias at US troops in Iraq, and through terrorist sleeper cells abroad. What's more, a US-led attack would only entrench the Iranian regime still deeper, not merely prompting it to accelerate its nuclear efforts but crowning it the lead Muslim victim of a western war against Islam. For now, thankfully, these arguments seem to be prevailing in Washington.
Which means the next 12 months could see the status quo hold, as the international community hopes that the stick of sanctions will make unnecessary the sharper stick of force. So far, their defenders say, sanctions are having an effect. The first two rounds, agreed by a 15-0 vote in the UN security council, sent a unified message to Tehran that the world was united against it - a position the Iranian elite cannot stand.
The trick is to learn from the disaster of sanctions against Iraq and to ensure they hit the right target. That's why Brown promised to tighten the screw on Iran's oil and gas industry and its financial sector. Sanctions are fraught, though. Russia and China gave their approval to the earlier, milder rounds but are foot-dragging now. Beijing has lucrative contracts with Iran and needs its oil; Moscow is in no hurry to avert a war that it believes would heavily reduce America's power in the world. The European focus now is on Germany: if it comes on board, then a joint US-EU raft of sanctions becomes possible.
Which brings us to the carrots. Some, though none now in government, reckon the way to deal with Iran is to shower it with carrots, to hug it into submission. One diplomat speculates that had Jack Straw remained as foreign secretary, he would have been to Tehran by now. His aim would have been to appeal to Tehran's wealthy, to have built up the pragmatists around former president Hashemi Rafsanjani and dangle the prospect of an Iranian return to the international fold. If that policy was pursued, runs the logic, Mahmoud Ahmadinejad would soon see his power drain away and he, along with George Bush, would be out of office by 2009.
No one in power is arguing for an all-hug strategy just now. Instead, it's promised as the reward for good behaviour. Note Brown's offer of "a transformed relationship with the world".
It all adds up to a delicate geometry, in which every element is connected: sanctions, the possibility of force, and the rewards that will come with compliance. The aim is to alter the Iranian calculus so that pursuing nukes becomes too costly, and giving them up too advantageous, to continue. It's subtle, tricky work - and as big a test of Brown's political agility as there will be. Unless something even harder comes along.