Bombers and fighter aircraft hit IS positions in seven strikes around Kobane, the scene of heavy fighting between the jihadists and Kurdish rebels near the Turkish border, US Central Command said.
The targets included IS units, staging areas, a heavy machine gun position, and five buildings held by the jihadist group.
The IS group has poured in reinforcements to try to overcome tenacious Kurdish resistance, and the fighting has threatened to cut Kobane from the outside world.
An air strike also hit an IS garrison northwest of the Syrian town of Raqa, according to the command, which oversees US military operations in the region. -AFP