Senior officials from the United States and Iran commenced negotiations on Saturday in Islamabad, with the help of Pakistani intermediaries.The talks are being held face-to-face between the US and Iranian delegations, Reuters reported, citing a Pakistani source.According to Iranian state media, Iran outlined its "red lines," which it insists Washington must accept before face-to-face talks can occur to resolve the six-week-old conflict.Pakistani Prime Minister Shehbaz Sharif on Saturday met