GENEVA - It was 4:40 a.m. Sunday when Iranian Foreign Minister Javid Zarif strode in to meet the world press in the fluorescent-lit Geneva conference center. He'd had little sleep over four-and-a-half days of grueling negotiations, yet he flashed reporters…

Margaret Warner reports from Geneva on the ongoing talks over Iran’s nuclear capability. The diplomats are struggling over the actual language of the text. Editor's note: This interview was recorded at 10:30 p.m. local Geneva time, before the agreement was…