The Israelis see no roll back of Iran’s nuclear capabilities; instead they envision Tehran being able to “break out” and make nuclear weapons at a time of its choosing. These concerns are, in all likelihood, shared by Saudi Arabia and other Arab powers in the Middle East.

In theory, these worries could be addressed. The key is to show that the pressure on Iran will not be eased. It should be made clear that vigorous enforcement of existing sanctions will continue, regardless of any interim deal – and if there is no final agreement at the end of the process, new restrictions will be added.

It is worth remembering that Mr Rouhani ran against the policies that produced Iran’s isolation when he won the presidential election in June. He pledged to get the sanctions lifted. The price for doing so is to change the character of Iran’s nuclear programme.

The emerging deal would limit the programme, but without changing it. So there is every reason to make clear that sanctions will not go away until the nuclear programme is greatly reduced, with verifiable mechanisms to detect any cheating – and they will actually be increased if there is no final agreement.