Two Syrian opposition figures say the ISIS group and al-Qaida's branch met last week and agreed to stop fighting each other and work together against their opponents.The deal could be a heavy blow to Washington's strategy against the self-proclaimed Islamic State of Iraq and al-Sham (ISIS) group, which is reliant on arming moderate rebel factions to push back extremists in Syria.A prominent Syrian opposition official and a rebel commander say delegates from the two groups met in secret on November 2 in northern Syria and agreed to end months of fighting between them and cooperate on the ground. The two spoke on condition that their names would not be made public, either for their own protection or because they were not authorized to release the information.