The most recent Islamic State offensive struck areas long controlled by Kurdish peshmerga forces, marking a rise in the efforts by the militant group and its allies to expand territorial control into Kurdish areas. Following strong initial resistance by the peshmerga, the Islamic State eventually overtook the areas. However, reports indicate that the peshmerga are planning a counteroffensive, and Baghdad has offered to provide air support.
Earlier advances by the Islamic State and its allies had indirectly aided Iraq's ethnic Kurds by giving them control of key areas, including Kirkuk, as large chunks of the Iraqi army in the north fled toward Baghdad. With the Islamic State's seizure of Mosul, an offensive toward Baghdad and clearing operations in Anbar, the Sunni militants appeared to favor a truce of convenience with the peshmerga. For their part, the Kurds were not interested in pushing much beyond their previously claimed lands. This temporary arrangement, however, was continually tested by sustained skirmishing between the two sides, particularly in eastern Diyala province and south of Kirkuk. It was not long before the skirmishing escalated into the recent battles.
In the past, the Islamic State has relied heavily on pick-up trucks equipped with medium and heavy weapons to carry out quick raids and outmaneuver heavier enemy forces. In Zumar, one of the towns seized Aug. 3, militants used these vehicles to surround, attack and overwhelm defending peshmerga fighters from multiple directions.
Aside from Zumar, the Islamic State captured the towns of Sinjar and Wana as well as the Ain Zalah oil field. The seizure of Ain Zalah adds to the number of fields under Islamic State control. The group already derives a lot of revenue from these fields. Currently, militants are also reportedly advancing on the town of Rabia near the Syrian border. This would further alienate Iraqi Kurdish areas from the Syrian province of Hasakah, where the Islamic State is engaged in heavy fighting with Syrian Kurdish People's Protection Units.
But these towns are not nearly as important as the Mosul Dam, which the group claims to have seized. The dam is the largest in Iraq and the fourth largest in the Middle East. It is not yet clear the extent of the group's control over the dam, but the commander of the peshmerga garrison that had been holding the dam confirmed the seizure and claimed that the dam workers remain in the facility. If true, this could put the Islamic State in a position to flood significant areas of northern Iraq, including the city of Mosul, located 50 kilometers (31 miles) to the south. During the 2003 invasion of Iraq, U.S. forces were particularly concerned that regime forces could demolish the Mosul Dam and cause significant damage. The current reported seizure brings the risk of this same scenario, although the Islamic State's control of Mosul and neighboring areas makes it less likely that militants will seek to breach the dam.
Despite its lack of dependable allies and its numerous enemies, Islamic State continues to threaten several regional factions and governments. At the same time, it needs to fight across a growing area of control, putting it at considerable risk of overextending itself. So far, the militants have proved adept at taking advantage of its enemies' divisions, using fear to overcome internal opposition and using geography and mobility to mitigate external threats. The group has also played on its perceived successes to attract an increasing number of dedicated foreign fighters to the region. The Islamic State's harsh rule still leaves it vulnerable to uprisings. But for now, the group is capitalizing on previous victories to maintain momentum as it enlarges its territory.