About six weeks ago Rafael Grossi, the head of the International Atomic Energy Agency (IAEA), warned that the attempt to revive the 2015 deal that restricted Iran's ability to enrich uranium was on the brink of collapse. Three or four weeks more without an agreement, he said, would deal the talks a "fatal blow".
The problem was that since ex-president Donald Trump unilaterally trashed the deal in 2018, imposing "maximum pressure" US sanctions against Iran in the hope of extracting further concessions, the Iranians have been gradually discarding the controls they agreed to in the original deal.
The three European countries that guaranteed the deal, Britain, France and Germany, backed the IAEA chief up, warning that "the more Iran is advancing and acccumulating knowledge with irreversible consequences, the more difficult it is to come back to that deal".
