The modest agreement on Iran’s nuclear programme with the US and its international partners is a rare, if provisional, piece of good news. The partial and tentative deal struck at talks in Geneva on Thursday sets up a roadblock on what was beginning to look like an inexorable path to confrontation with the Islamic Republic. It could even open up a broader avenue of engagement, by addressing the security concerns of Iran, its neighbours, and the west.

The recent disclosure of another undeclared nuclear site near Qom ratcheted up the tension. But it has also forced the antagonists to focus more intensely on Iran’s nuclear ambitions – on the endgame, on how to get there, and on the stark alternative of conflict.