Yukiya Amano, of the International Atomic Energy Agency, said some details still needed to be worked out. But he told reporters that Iranian officials say that those will not stand in the way of signing the deal.

“(A) decision was made to conclude and sign the agreement … I can say it will be signed quite soon,” he said.

Amano spoke Tuesday on returning from Tehran, after talks on resuming a long-stalled probe into suspicions that Iran secretly worked on developing nuclear weapons.