Iran sanctions: Last throw of diplomatic dice?
New European Union sanctions are finally targeting the engine of the Iranian economy: oil and gas.
New investment by EU companies is being banned, and the list of banned items is being extended to include so-called dual-use equipment - pipes that could be used for military purposes, for example.
There are also other financial measures.
They add to similar action taken by the United States recently. These both go further than four rounds of UN sanctions, all of which avoided taking action against Iran's energy sector, mainly because of Russian and Chinese objections.
But if they fail to bring Iran to the nuclear negotiating table, what then? Is this the last throw of the diplomatic dice?
Already, the distant drum beats heralding war talk are beginning to sound.
In Washington, for example, Gen Michael Hayden - who was head of the CIA from 2006-09 - said that under President George W Bush, an attack on Iran was "way down on our list".
But now, he told CNN, he thought this "may not be the worst of all possible outcomes".
"We engage. They continue to move forward. We vote for sanctions. They continue to move forward. We try to deter, to dissuade. They continue to move forward," he said.
The latest attempt to change Iran's policy is based on the hope that, in the end, the cost of not negotiating an end to its enrichment of uranium will be too high.
The Iranian government largely depends on oil and gas revenues and, in particular, is short of refined petroleum products, much of which it has to import.
But so far, this approach has not worked. Iran seems to thrive on opposition to pressure. It says it will continue to enrich uranium and denies that it intends to make a nuclear bomb.
It has now suggested restarting talks on the provision of fuel rods for its medical research reactor, but that would not address the basic issue of its enrichment programme.
The new measures will have to be given time to take effect. This means months at least, if not much longer. The US and EU hope that there will be a cumulative impact as more international companies stop doing business with Iran.
And there are huge loopholes in the sanctions. China and Russia refuse to accept measures against oil and gas. China remains one of Iran's best customers and, faced with the task of feeding and supplying its vast population, will inevitably put its own interests first.
A key point made by Gen Hayden was whether Iran's critics could live with a formally non-nuclear Iran.
It would be just below the nuclear weapons threshold, where the needle was "not quite in the red", as he put it, but able to break out and make the final steps at short notice.
The general felt they would not. But the alternative, military action against Iran's nuclear facilities, might well provoke a conflagration in the region.
It is likely that Iran will be constantly reminded that there is a negotiating package on offer under which it would be given help to develop a civilian nuclear industry. But it has shown no interest in this.
The stand-off continues.