OSLO — At a corner table of the Marriott Hotel in Pakistan’s capital, an emissary from the Taliban’s supreme leader arrived with a message of peace.It was 2007, as the Afghan Taliban insurgency was growing bolder. The United States-led international coalition was fixated on defeating the Taliban militarily, and that mission would only intensify when President Obama sent in tens of thousands more troops starting in 2009.But that evening at the Marriott in Islamabad, the talk was about diplomacy, and there were no Americans in the room. Alf Arne Ramslien, a senior Norwegian diplomat who had cultivated relationships and trust within the Taliban for years, was meeting with a confidant of Mullah Muhammad Omar, the movement’s reclusive founder, who was directing the insurgency from exile in Pakistan.The Taliban emissary gave Mr. Ramslien a list of five names that Mullah Omar had tasked with exploring the possibility of peace talks. They needed the help of a facilitator, he said, and Mr. Ramslien was it.