The decision yesterday by the European Union to ban imports of Iranian oil from July has sparked renewed threats from Tehran to close the Strait of Hormuz. It makes even more perilous a confrontation that could yet lead to war, even before a Western attack on Iran's nuclear facilities.
The impact of an EU embargo, given the global nature of the oil market, cannot be measured precisely. Beyond doubt, however, it will tighten the squeeze on Iran's economy, already in deepening trouble. Meanwhile, Washington has warned Tehran, both publicly and through private channels, that any closure of the Strait, through which a fifth of the world's crude oil supplies are shipped, would cross a "red line" – meaning the US and its allies would use force if necessary to keep them open.
Nor are matters helped by the baying for military action from ill-informed Republican candidates on the 2012 campaign trail, as they pander to the powerful evangelical Christian and Israeli lobbies in search of votes. President Obama has thus far played a difficult hand with impressive steadiness. Early in his term, he offered direct talks without preconditions (which Tehran stupidly turned down), and has resisted demands from the Netanyahu government for a pre-emptive strike against installations at Natanz, Isfahan and elsewhere. All the while, he has steadily intensified sanctions. But, in an election year, the pressure on Mr Obama to be "tough on Iran" will only grow. As tensions increase, it is vital to remember that the West's goal is to bring Iran not to the battlefield, but the negotiating table. Iran is seeking nuclear weapons, to be sure, but is still some way from getting them.
The sanctions targeting the central bank, and now its all-important oil exports, are clearly working. Iran's internal politics are in turmoil, its key regional ally Syria is in danger of imploding, and some Iranian politicians say they are willing to talk. A mission next week by senior inspectors from the United Nations' nuclear watchdog agency offers an early opportunity to test their sincerity. In short, the time for a deal has not yet run out. Nor must our patience.