US action in doubt as IS tightens grip on city

Islamic State fighters tightened their grip on the historic city of Palmyra in Syria, days after capturing a provincial capital in neighbouring Iraq, hinting at the momentum of the group, which a monitor says holds half of Syrian territory.

The twin successes pile pressure not just on Damascus and Baghdad, but also throw doubt on US strategy to rely almost exclusively on air strikes to defeat Islamic State.

Extending its reach in the region, fighters loyal to the Sunni Muslim group have also consolidated their grip on the Libyan city of Sirte, hometown of former leader Muammar Gaddafi.