By Roger Hardy
BBC Middle East analyst
Sectarian tensions are high in the Mosul area of northern Iraq following the killing of 23 members of the Yazidi minority.
Yazidis are viewed with suspicion by other religious groups
The Mosul area has long been religiously mixed. It is home to a variety of Muslim and Christian communities, as well as to the Yazidis - a small, ancient heterodox sect who are ethnic Kurds.
Yazidis are to be found in Iran, Russia and Turkey, but the largest number are in northern Iraq.
Traditionally the different communities in and around Mosul have lived together in relative harmony.
But now there is a new tension in the area, focused on the village of Bashika, which is mainly Yazidi with Christian and Muslim minorities.
Cycle of killings
The trouble started when a Yazidi woman from the village recently converted to Islam and ran off with a Sunni Muslim man.
This was not the first incident of its kind, and the woman's relatives were so incensed that they kidnapped her, brought her back to the village and stoned her to death.
Sunnis, and the local police, demanded the villagers hand over the culprits to face justice, but the villagers refused.
On 22 April, gunmen - presumed to be Sunnis - stopped a bus bringing textile workers from Mosul back to the village.
They separated 23 Yazidis from the others and shot them dead.
According to an eyewitness, the gunmen shouted at the Yazidis, "God curse your devil".
Some Muslims regard Yazidis as devil-worshippers because they revere an angel in the form of a blue peacock.
It appears the dispute is local - though there is some speculation that insurgents are trying to drive a wedge between Muslims and Yazidis.
Minorities in peril
The incident has worrying implications.
It is one more sign that Iraq is not just in the grip of a cycle of violence involving Sunni and Shia Muslims.
Unlike Christians, most Yazidis have stayed in Iraq
It faces a broader sectarian problem now affecting some of the country's oldest minorities.
Following attacks on Iraqi Christians, many have fled the country.
Christian doctors, academics and other professionals have been targeted either out of sectarian hostility or by criminal gangs carrying out kidnappings for ransom.
Those who remain live in fear, especially after the killing of two elderly nuns last month in the northern city of Kirkuk.
The Yazidis, in contrast, have largely stayed put.
Once a mosaic of religious and ethnic groups who enjoyed a largely peaceful coexistence, Iraq is increasingly falling prey to sectarian suspicion and intolerance.