US assassinates Islamic State 'second leader' in Syria

A key military commander for the Islamic State group in Syria has been killed in an airstrike carried out by the US-led coalition, the Pentagon said on Thursday.

Abu Jandal al-Kuwaiti died on Monday near Tabqa Dam, west of the IS stronghold of Raqqa, according to a statement from Centcom, the US military command in the Middle East.

Rami Abdel Rahman, head of the Syrian Observatory for Human Rights monitoring group, described al-Kuwaiti as the "number two military commander for IS in Syria."

The extremist commander led battles in Iraq and Syria, and was most recently assigned to Raqqa where he oversaw attacks on the Syrian Democratic Forces (SDF), the Observatory said.

The SDF, an Arab-Kurdish alliance backed by US ground and air forces, launched an offensive to retake Raqqa in early November.

Al-Kuwaiti was involved in using suicide vehicles, IEDs and chemical weapons against the SDF, Centcom said.

He was previously a member of the IS "War Committee" and involved in the group's retaking of the central Syrian city of Palmyra on December 11, just eight months after the army backed by Russia drove them out.

Centcom added that al-Kuwaiti's death would impede the militant groups' ability to defend Raqqa, as well as diminish the group's ability to launch attacks in the West.