President Barack Obama on Wednesday sought to rally the world and especially Muslim countries to join the American fight against ISIS militants — a “network of death” that he said must be destroyed. Speaking at the United Nations, two days after the United States escalated its campaign against the militants with a barrage of airstrikes in Syria, Obama called on countries to counter the extremism and sectarian conflict that allow terrorism to flourish. “No God condones this terror,” he told the General Assembly in New York. “No grievance justifies these actions. There can be no reasoning — no negotiation —...