Sanctions are a blunt instrument, at best. Given the history, from the botched measures against Iraq in the 1990s to the decades of futile pressure on Cuba, the strengthened sanctions levelled against Iran's nuclear programme in recent months have shown considerable results. As The National's columnist Afshin Molavi wrote earlier this week, the EU boycott scheduled to begin on July 1, coupled with cutbacks by Asian customers, could reduce demand for Iranian oil by as much as one third.
That will exert considerable economic pressure on Tehran. The signals, admittedly still hazy, are that Iran's leaders are considering making concessions at nuclear talks that are continuing in Baghdad next week.
The new US sanctions, announced by President Barack Obama in December, have been effective precisely because they are targeted. Major banks are refusing to do business with Iran, while insurance companies have stopped providing cover for tankers transporting Iranian oil. Combined with the reduction in demand, all of this is making Iran's business of energy exports much more difficult.
It is worth being crystal clear: these sanctions are not punitive; they are meant to influence behaviour - in this case, deter the development of an Iranian nuclear weapon capability and a regional arms race. Economic sanctions are meant, ultimately, to encourage an agreement.
In the US Senate, this message is not being understood. As reported by Reuters yesterday, the Senate Democratic leader Harry Reid is calling for a new round of measures against foreign banks that deal with Iran's energy sector. To be sure, closing loopholes in the existing sanctions regime makes sense, but a very public drubbing of Tehran in the US Congress, one week before talks, could be counterproductive.
In an election year, US politicians are falling over themselves to prove their hawkish credentials. Not surprisingly, the proposals are backed by the pro-Israel lobby Aipac, which is pushing for Republican support.
The effectiveness of sanctions has had the added benefit of dampening the drumbeat of war in the US and Israel. There is a real chance to defuse this stand-off in the next series of talks. Iran has a history of duplicity in negotiations but certain concrete steps - nuclear inspections and cooperation on uranium-enrichment controls - could go a long way to allaying fears.
It is not just the Americans who are playing to the domestic audience. Iran's nuclear negotiating team, and Supreme Leader Ayatollah Ali Khamenei, will have to justify any concessions to their constituencies. American bullying at this stage could make that practically impossible.