After months of being targeted by U.S.-led airstrikes, losing ground in Iraq and suffering defeat in a weeks-long assault to capture the Syrian border town of Kobani, is the Islamic State flagging and putting out feelers to see if a truce might be possible? Or is it just seeking to sow confusion in the ranks of its opponents and to undermine their unity and resolve by raising the idea of negotiations? Intriguingly, the Islamic State, also known as ISIS or ISIL, floated the idea on Tuesday of a negotiated truce in the latest issue of the militants’ English-language magazine Dabiq,...