Iran is undoubtedly a source of instability and conflict in the Middle East, and a real danger to Israel. But present United States policy to deal with these issues is misconceived and likely to make them worse. President Donald Trump has initiated a programme of severe economic sanctions designed to bring Tehran to heel. In so doing he has undermined the agreement negotiated by his predecessor in alliance with the European Union, which was working, and replaced it with a policy of confrontation, which is not.

The agreement had persuaded Iran to wind back its nuclear ambitions, in particular the production of enriched uranium which would be a key component of Iranian nuclear weaponry. Tehran has announced that unless the other parties to the agreement can make good the harmful effects of American sanctions – which realistically they cannot – enrichment is to be stepped up. It is a form of nuclear blackmail.

It is also becoming apparent that the harassment of shipping in the Gulf of Oman is being used as an extra pressure point, though the Iranian government implausibly denies being responsible.