More footage of US airstrikes on Islamic State positions in Syria have emerged, as Kurdish forces continue their desperate battle to fend off the approaching jihadi forces.

US and allied forces from Arab states have been bombing IS positions in Syria since last week, after the US expanded its air campaign against the terrorist group; until then the operation had been focused on blunting the Islamists' advances in only Iraq.

Several European countries - including Great Britain - have joined that campaign, but have limited their support to the Iraqi theater alone, where allied forces have been invited to operate by the Iraqi government. In contrast, the US has ignored demands by the Assad regime in Syria, which it views as illegitimate, for airstrikes to be coordinated with pro-government forces and has instead operated without Damascus's consent.

But while airstrikes in Iraq - coupled with a ground coalition made up of Kurdish Peshmerga forces, Iranian-backed Shia militias and the Iraqi army - have succeeded in slowing down and even halting IS's advances there, airstrikes in Syria appear to have been ineffective thus far.

Kurdish fighters from the People's Protection Unit (YPG) are fighting tooth-and-nail to keep IS from seizing the Kurdish town of Kobane, which sits on the Syrian-Turkish border. Coalition airstrikes in Syria have targeted both IS's de facto capital of Raqqa, as well as the IS front lines with the YPG, but those latter strikes appear to have had no noticeable effect on the battle, with IS now moving to within just three miles of the town.

Kurdish leaders have warned of a renewed threat of genocide should IS gain control of Kobane.