By mid-December 2015, the battlefield around the
Islamic State controlled city of
Mosul had shifted decisively against the Islamic State following the Kurdish recapture of
Sinjar in November 2015. That victory, along with the wider
offensive on Mosul's outskirts by the Peshmerga that had happened earlier in 2015, had severed one of the Islamic State's key supply lines between Mosul and Syria, especially
Raqqa, and placed sustained pressure on its northern defensive belt. Kurdish
Peshmerga units were steadily advancing along the Nineveh Plains, threatening to tighten a noose around Mosul’s eastern and northeastern approaches. However, disagreements between Kurdish and Iraqi forces slowed the process of expelling the Islamic State from Mosul. The Kurds thus appealed to the U.S.-led international coalition for more military support in its fight against the Islamic State. Western officials, including
Ashton B. Carter, were in the region meeting Kurdish leadership in
Erbil at the time, which underscored the growing strategic importance of Kurdish operations. == Offensive ==