The United States and its allies launched 23 air strikes against Islamic State (Isis) targets in Syria and Iraq on Thursday (1 January).
Air strikes in and around the Syrian cities of Kobani, Raqqa and Hasakah hit vehicles, buildings and fighting positions as well as a unit of militants, the Combined Joint Task Force said.
The air strikes in Iraq also targeted vehicles and buildings, as well as a weapons cache.
Militants aligned with the so-called Islamic State have seized territory in both Iraq and Syria, declaring the establishment of a cross-border Islamic caliphate in the summer.
The US organised a coalition of Arab and Western states to launch air strikes against the militants after they seized Iraq's second city of Mosul in June 2014.