RAMADI, Iraq — Meeting various neighbors and supplicants on a recent evening, America’s staunchest ally in Iraq, Sheik Ahmed Abu Risha, sat in a tent sipping tea from an implausibly tiny glass cup. He greeted each new visitor with a hearty outburst of “dear one” and a kiss on the cheek.

At one point a young man walked in carrying an M-16 rifle, leaned over and kissed the sheik on the cheek, too, in a clear sign of loyalty from a member of a tribal militia.