Islamic State forces are attacking the strategic Kurdish border town of Kobani on three sides, as officials say that US air strikes are failing to drive the terrorists back.

ISIS has already penetrated the city's defenses and the Kurdish militia, the YPG, is reportedly falling back.

Meanwhile, Turkey has massed some troops on their side of the border and say they will not allow Kobani to fall into ISIS hands

Guardian:

US-led air strikes in northern Syria have failed to interrupt the advance of Islamic State (Isis) fighters closing in on a key city on the Turkish border, raising questions about the western strategy for defeating the jihadi movement.

Almost two weeks after the Pentagon extended its aerial campaign from Iraq to neighbouring Syria in an attempt to take on Isis militants in their desert strongholds, Kurdish fighters said the bombing campaign was having little impact in driving them back.

Isis units have edged to within two kilometres of the centre of Kobani, according to Kurds fighting a rearguard action inside the city. The jihadis, who this weekend generated further outrage with the murder of the British hostage Alan Henning, are simply too numerous to be cowed by the air assault by US fighter jets, the Kurds say.

“Air strikes alone are really not enough to defeat Isis in Kobani,” said Idris Nassan, a senior spokesman for the Kurdish fighters desperately trying to defend the important strategic redoubt from the advancing militants. “They are besieging the city on three sides, and fighter jets simply cannot hit each and every Isis fighter on the ground.”

He said Isis had adapted its tactics to military strikes from the air. “Each time a jet approaches, they leave their open positions, they scatter and hide. What we really need is ground support. We need heavy weapons and ammunition in order to fend them off and defeat them.”

The Britain-based Syrian Observatory for Human Rights has reported that warplanes have carried out repeated strikes in recent nights around Kobani. The Pentagon has reported daily on its aerial missions over Iraq and Syria since first deciding to go after Isis two months ago. But it does not pinpoint exact locations. “Two strikes north-west of Raqqa struck a large (Isis) unit and destroyed six firing positions,” it said on Sunday in a statement. Kobani is north-west of Raqqa.

But the claim that the aerial bombardment is not sufficient to turn the tide on the ground will unsettle those in the US-led coalition, including the UK government, who have signed up to an air war as the best way of taking the fight to Isis.

The Turkish government has already voted to allow ground troops to fight in Syria, so, if the reports of the Kurds falling back are accurate, intervention by Ankara may be imminent.

Why is Kobani so important to ISIS? CNN explains:

SIS is getting closer to capturing a key city that would mark not just a huge strategic victory, but would also deal a devastating blow to the Syrian Kurds trapped by the group's violent campaign.

The city of Kobani sits near the Turkish border and would give ISIS a complete swath of land between its self-declared capital of Raqqa, Syria, and Turkey -- a stretch of more than 100 kilometers (62 miles).

Turkey has a modern NATO army but is untested in battle. And there is going to be some hesitancy in throwing in with the Kurds, who they have fought a low intesnity conflict for years. So far, Prime Minister Erdogan has refused to allow the Kurds to purchase the heavy weapons that would allow them to face ISIS on more equal terms. This policy is likely to continue as Ankara does not want to see those heavy weapons turned against them by Kurds who have been struggling to break free.

If Kobani falls, it will be a huge blow to the US strategy of fighting ISIS from the air. The pinpricks we are giving ISIS are proving to be inadequate against a foe who has adopted new tactics to minimize damage from the air strikes while continuing its advance on the ground.