BAGHDAD — Sunni extremists seized control of three towns in northern Iraq on Sunday after fierce battles with Kurdish security forces, sending thousands of people fleeing to the nearby mountains and threatening the country’s largest dam.
In the darkness of Sunday morning, the Sunni fighters swept in to take one of the towns, Sinjar, and set about their method of conquest that is as familiar as it is brutal: They destroyed a Shi’ite shrine, executed resisters, overran local security forces, and hoisted the black flag of the Islamic State of Iraq and Syria above government buildings.
Hours later, as the militants demanded that the city’s residents swear allegiance to the Islamic State or be killed, the group’s social media campaign was underway, with photos posted online showing militants patrolling the city’s streets.
The UN representative in Baghdad, Nickolay Mladenov, issued a statement Sunday afternoon, citing reports he had that as many as 200,000 civilians, mostly from the minority Yazidi community, had fled the new fighting.
“A humanitarian tragedy is unfolding in Sinjar,” Mladenov said.
In the face of stiff resistance from Shi’ite militias aligned with Iran that have stalled their march on Baghdad, the Islamic State fighters who captured Mosul in June pushed north this weekend, and by Sunday afternoon they were in control of two other towns after fierce battles with Kurdish security forces, known as the pesh merga, who have been increasingly thrust into battle to defend the border of their autonomous region in northern Iraq from encroachments by the Islamic State.
In a statement, the Islamic State boasted of conquering “more important areas which were controlled by the pesh merga and the secular militias.”
With the new territory, which the group described as “the border triangle of Iraq, Syria, and Turkey,” the Islamic State has strengthened its hold on territory that traverses the frontiers of Iraq and Syria, giving it a greater ability to move fighters and weapons between the front lines of the civil wars in both countries.
According to security officials and residents in the area, the Kurdish forces were routed from Zumar, a town amid oil fields along the road from the Syrian border, and then Sinjar, an isolated city in northwestern Iraq.
Sinjar has been home to a sizable community of Yazidis, Kurdish speakers who ascribe to a religion that combines elements of Islam and ancient Persian religions and who are considered apostates by Muslim extremists.
Later Sunday, the militants captured Wana, a strategic town near the Tigris River — putting them within striking distance of the Mosul Dam, the country’s largest and an important supplier of electricity and water. The dam is on the Tigris River about 30 miles northwest of Mosul, Iraq’s second-largest city, which fell to the Islamic State on June 10.
Yazidi residents of Sinjar, who were reached by phone, were terrified. They told of kidnappings and executions of members of their group. One resident, Sami Hassan, said he was at work as a nurse at a hospital Sunday when an injured Islamic State fighter arrived and demanded to know the sect to which Hassan belonged.
Hassan said he escaped from a window while being shot at.
Another local resident, Khudhur Rasho, said he had seen two Yazidi men executed and the members of 10 families, their hands bound behind their back, being led away by militants.
The seizure of the three towns in a triangle that stretches north and west from Mosul to the borders of Syria and Turkey allowed the extremists to expand their territory, but the capture of the Mosul Dam would be a bigger prize.
On Sunday, conflicting reports emerged about who was in control of the dam, with some local news media reporting it had been captured by the Islamic State. But Kurdish officials and an official at the Ministry of Water Resources in Baghdad denied those reports.
Keeping important infrastructure out of militant hands has been a priority of the Iraqi government.