"When it finally came late on a Saturday night, the announcement was momentous: the Iran nuclear deal had entered into force," writes AFP's Vienna-based correspondent Simon Sturdee, who spent countless days covering the ins and outs of the oft-tortuous diplomacy.

"The UN atomic watchdog announced that yes, Iran really had curbed its nuclear programme. Sanctions were lifted and after 13 years, a dangerous standoff was over.

"But for me, who has covered the ins and outs of the story for nearly five years, this was also a moment tinged with sadness -- the twisting, fascinating and often infuriating saga was finally over. Well, probably."