The US military conducted air strikes in Libya on Monday following a government request to target the Islamic State group's Libyan stronghold of Sirte, the Pentagon announced.

"At the request of the Libyan Government of National Accord, the United States military conducted precision air strikes against ISIL targets in Sirte, Libya, to support GNA-affiliated forces seeking to defeat ISIL in its primary stronghold in Libya," Pentagon press secretary Peter Cook said in a statement, using an acronym for the IS group.