Islamic State: What has Kobane battle taught us?

Kobane has been hit by dozens of airstrikes

After a month of fighting, defenders of Kobane say Islamic State (IS) has been virtually driven out of the Syrian town. So what has been learned from this battle?

1. Kobane is not "strategically" important.

At least not in the classic sense of that word. It will not decide the fate of the Syrian civil war or indeed of the Pentagon-led campaign, designated Operation Inherent Resolve, against IS.

The primary importance of Kobane, a town populated by Kurds on the border with Turkey, lies in the scale of human misery that the battle and its displacement of 250,000 people has created.

This has had knock-on effects on the Kurdish relationship with Turkey, where most of those people have gone.

Turkey has been trying to push forward a peace process with its own Kurdish population following a long insurgency.

The battle has also aggravated Turkey's relationships with its allies. In terms of a win for IS, it is in aggravating these tensions that Kobane comes closest.

2. Both IS and the Pentagon chose to fight there for propaganda reasons.

As far as the US-led coalition is concerned, Syria comes second, for the time being at least.

General John Allen, co-ordinating the campaign, noted on Wednesday that "the emergency in Iraq right now is foremost in our thinking".

But if that's true, why have there been so many air strikes around the Kurdish town?

Central Command says there have been dozens this week, with 14 between Tuesday and Wednesday.

The battle has undoubtedly presented IS with a chance for a big propaganda win and, therefore, the coalition with a need to deny them that gain.

Whether or not Kobane holds out long term, the US and its allies have now used it as an opportunity to show solidarity with the Kurds and pummel their mutual enemy.

By avoiding a commitment to hold the town, and even implying that it's likely to fall, US commanders have tried to deny any propaganda advantage.

A number of Kurds have been killed and 250,000 displaced

3. Geography has been critical.

It is Kobane's location on the Turkish border that has prevented it turning into a siege in the true sense of it being surrounded.

It is also its physical location that made it the subject of worldwide TV coverage, as journalists have watched the battle unfolding from nearby hilltops in Turkey.

This proximity has allowed fighters to come in and out and some limited re-supply. In the last extreme it would allow the town's defenders to escape.

The Kurds have made many accusations against the Turkish authorities on the border, including that they have prevented re-supply and disarmed their fighters trying to leave Syria.

There is considerable truth in this, as those fighting across the border in Syria are an arm of the same movement as Turkey's domestic Kurdish enemy, the PKK.

But journalists in Suruc, the nearby Turkish frontier town, have met fighters who have been passing back and forth.

It is also reasonable to infer that Kobane's defenders would have run out of ammunition by now if re-supplies had not been coming across the border.

One well-placed Turk told me that supplies had indeed been allowed across.

There's one more intriguing aspect to the geography. It is also, almost certainly, helping the coalition to achieve its high strike rate in the town.

Whether the eyes doing the targeting are actually in Turkey or have crossed into Kobane itself may not become clear for a long time.

But the rate of air strikes, accuracy, and general absence of drones over the area all point to targeting from the ground.

Of course all of these geographic factors underline the difficulty in achieving the same effects somewhere deeper in Syria.

Events in Kobane have been monitored by Turkish forces

4. By concentrating in one area, IS gives its enemies the opportunity to kill them.

The Pentagon claims to have killed "hundreds" of jihadist fighters in the town.

Whether or not this is an over-estimate, reliable reporting in the past 36 hours suggests some kind of pull-back by IS.

Are they just re-grouping or is the fight proving too costly?

The anti-IS campaign so far has actually had great difficulty in generating the kind of intelligence that allows effective strikes.

That and the dispersal of IS fighters among civilian communities are the prime reasons why 90% or so of the missions designated for bombing have not released their weapons.

But when the IS fighters gather for an assault, opportunities are created for the US and its allies.

This happened in the open territory around Iraq's Mosul dam at the start of the campaign against IS, and again in Kobane, where the evacuation of most civilians has allowed strikes to go ahead at low risk to them.

There can be little doubt that many or even most weapons dropped there have struck home.

Crowds have shouted anti-IS slogans from the hillsides in Turkey

5. By distracting IS from the battle in western Iraq, it is in the coalition's interest to keep Kobane going for as long as possible.

Recent gains by the militants in the Iraqi province of Anbar have caused the most worry to the Pentagon.

These have shown the continued weakness of the Iraqi army, and exposed the remaining Sunni tribal allies of the Baghdad government to massacre.

This week, US advisers have been inserted into some of the Iraqi bases that are still holding out in Anbar, and one in Diyala province too.

The aim is to co-ordinate a much more aggressive air effort than has been possible up to now.

In this sense, the Americans have been using air power in Kobane, away from where they really need it, because they have lacked the means to target IS in Anbar with the same intensity.

For IS though, the Kobane battle acquired its own logic, drawing in heavy weapons such as tanks and artillery, that might have been better used elsewhere.

Each side has had its own reasons for continuing the fight in the Syrian town.

But even an IS-friendly assessment of the battle would have to conclude that it had been long and difficult and hardly the kind of whirlwind victory that it won time and again in northern Iraq back in June.

Areas surrounding Kobane have also been hit from the air