breaking newsAirstrikes on towns in northern Iraq seized by Islamist militants began late Thursday in what Kurdish and Iraqi officials called the first stage of an American-led intervention to blunt the militants’ advance and provide emergency aid to tens of thousands of refugees. Kurdish and Iraqi officials attributed the bombing campaign to American forces. But the Pentagon firmly denied that American forces had begun a bombing campaign. Pentagon officials said it was possible that allies of the United States, either the Iraqi or Turkish militaries, had conducted the bombing. A Turkish official said the country’s air force had not conducted any operations. The official, who spoke on the condition of anonymity, said Turkey had been helping the Kurdish regional government in northern Iraq with humanitarian supplies. “There is no such thing,” he said, referring to airstrikes. More