Iran's threat to restart the process of enriching uranium has kept the world guessing about its ultimate intentions and has put its opponents on the back foot again.
Iran said the suspension of nuclear activities was only temporary
Its obfuscation is in keeping with its past tactics.
The one thing Iran has not offered in this whole saga is clarity.
Yet without clarity, nobody knows how to respond - not the US, nor the European countries negotiating, with grudging US support, with Iran - Britain, France and Germany - nor the International Atomic Energy Agency (IAEA), nor the Russians nor the Chinese, let alone the UN.
The sophistication of the Iranian threat is shown in the limited steps it proposes to take.
This would involve the conversion of crushed uranium ore (yellowcake), which it already has, into uranium hexafluoride, a gas that then has to be spun in centrifuges to separate the parts needed for nuclear power.
It could argue that conversion is a "pre-enrichment" process.
That argument has already been dismissed by the European Union Three (EU3) who say that under an agreement last November, Iran agreed to suspend all enrichment "activities" while holding talks about agreeing "objective guarantees" that its future nuclear power programme would be peaceful.
Quite why the threat has resurfaced at this moment is not clear. Nor is it clear why the threat was not carried out immediately.
It could be that Iran thinks that its talks with the three European countries are getting nowhere and that this is a way of trying to get some progress.
It might have wanted to test the waters to see what might happen next. There could even have been disagreements in the Iranian government itself.
It could also be that the Iranian presidential elections next month have something to do with it.
The previous president, the conservative though pragmatic Hashemi Rafsanjani, has announced that he is to stand and maybe the threat is part of manoeuvring connected to that.
One theory is that uncertainty would be good for him as he is an experienced hand and Iranians might vote for experience.
But nobody really knows and diplomacy is reduced to guesswork.
"I thought the Iranians would wait until after the presidential elections, " said Dr Gary Samore of the International Institute for Strategic Studies (IISS) in London.
"But maybe they have decided to have the confrontation sooner rather than later. They might think they are strong enough anyway. Alternatively, they might resume activities now only to suspend them again later."
The only clarity has come from the EU3, supported by the United States. They have said that if Iran does resume enrichment, then a special meeting of the IAEA governors will be called with the intention of reporting Iran to the Security Council for violating the Nuclear non-Proliferation Treaty in the past.
Tehran insists its nuclear programme is entirely peaceful
If the Security Council orders Iran to stop enrichment and it does not, then it could face sanctions.
These could include an arms embargo, a ban on nuclear co-operation and restrictions on investment in oil and gas development.
But it is a big if, given that Russia and China would have to agree.
Russia is itself involved in completing a nuclear power station in Iran and China buys a great deal of oil from Iran.
The risk is that Iran is simply acting tactically and that strategically it still intends to master the technology of the full enrichment cycle.
If that is the case, it will have to declare its hand at some stage and face the consequences. Ultimately these could go beyond UN sanctions and could involve a threat by Israel to attack Iran's nuclear facilities.
Iran argues that under the NPT, a country wanting to develop nuclear power - and that is all it wants to do, it claims - is allowed to enrich its own fuel.
This is true, but Iran's problem is that the IAEA has established that it hid an enrichment programme for nearly 20 years.
The US and the EU3 now argue that it cannot be trusted and must therefore not be allowed to enrich.
In their view the only effective "objective guarantee" would be to have no enrichment at all.
They reject the increased inspections that Iran is offering as inadequate.
This is because the same technology used to enrich uranium to a level needed for nuclear power can also be used to enrich to a level needed for a nuclear bomb.
If Iran were allowed to develop an enrichment cycle, it would be able to use the technology to make a nuclear bomb in due course, at a time of its own choosing.