What's at stake as Kurds, Islamic State, and US fight over Kobane? A lot.

A look at what victory or defeat would mean for the self-styled Islamic State – and for US objectives in its expanding war in Syria and Iraq.

What's at stake in Kobane, the ethnic-Kurdish city in Syria, where soldiers from the so-called Islamic State have battled Kurdish resistance for weeks now?

While US Secretary of State John Kerry said yesterday that saving the hillside town just over the border with Turkey was not a "strategic" priority for America, IS apparently feels differently. And for good reason. Their advance on the Kurdish Iraqi city of Erbil in September was reversed, thanks in part to US air support and Iranian ground support to Kurdish fighters. This setback pierced the aura of inevitability and invincibility that the group had developed following its seizure of Iraq's second largest city, Mosul, in June.

A victory – any victory – for IS in defiance of US efforts would go some way to restoring their sense of momentum. It would also spread fear, a key factor in persuading Iraqi soldiers and panicked civilians and local militias to flee when the group advances. Forcing another 100,000 Kurdish refugees into Turkey would generate horror and anger overseas, and show the price to be paid for defying the Sunni jihadists. 

The same dynamic is at play with their videotaped murders of captives, many by beheading. Savage? Yes. But that's the point. The group, which evolved from the Sunni jihad resistance in Iraq after the US toppled Saddam Hussein, has been using beheadings to cower Sunni Arabs, Kurds, and Shiite Arabs alike for a decade now.  

And there is true "strategic" value to Kobane for both IS and its Kurdish opponents, the YPG. This Syrian Kurdish militia is allied to Turkey's Kurdistan Workers' Party (PKK), a Marxist-movement deemed terrorists by both the US government and Turkey, and which has fought effectively against IS in the Kurdish parts of Iraq and Syria, including the defense of Erbil. 

Capturing Kobane would hand the jihadists control of nearly half of the 500 mile long border between Turkey and Syria, a crucial conduit for foreign fighters joining its cause. 

A Kobane in the hands of the YPG, on the other hand, would leave an enemy Kurdish enclave in the Islamic State's rear in Syria, as the US-led bombing campaign ramps up. The border would give the Kurds a way to rearm their fighters and eventually become strong enough to threaten the IS-controlled Syrian town of Tel Abyad further east.

As Carl Drott writes on the Syria Comment blog of Joshua Landis, who studies Syria at the University of Oklahoma:

The capture of (Tel Abyad) would enable the isolated Kobani enclave to be connected with the much larger Jazira area that also borders the Kurdistan Region in Iraq (a successful attack would most likely come from this side). For IS, on the other hand, getting expelled from this area would mean losing all access to Turkey east of Jarabulus.

Another goal for YPG would be to capture the eastern shore of the Euphrates. Not only would this mean a huge security improvement, but it would also give much-needed access to water. A station near Shiukh used to pump water to Kobani, but IS cut the supply completely when it took over the area early this year. The Kurdish administration then connected deep new-dug wells to the water treatment plant in Qaraqoy. These facilities have now also been captured by IS, which means that Kobani’s only water supply comes from smaller wells inside the town itself.

What other strategic interests are in play?

The battle for Kobane – and other aspects of the US campaign in both Iraq and Syria – illustrates a fundamental reality of this conflict. While US war planes have repeatedly dropped bombs in and around Kobane to aid Kurdish resistance against IS, Pentagon spokesman John Kirby said yesterday that air power alone wasn't enough to save the town.

That observation is uncontroversial to everyone watching the unfolding situation, including reporters perched on a hill overlooking the area on the Turkish side of the border. But it applies more broadly to the White House's overall effort in areas now under IS control. It's obviously useful for IS to show that it can't be defeated by air power. And it's a reminder that a ground effort by US or other foreign forces, or properly equipped local fighters, is necessary.

But Turkey stands in the way of all of this. While Kurdish civilians and reporters have watched the situation from the border with horror, Turkey's military is focused on preventing Kurdish fighters from the PKK from crossing into Syria to link up with Kobane's defenders. Turkey's priority, unlike America's, is not the defeat of IS. Instead, Turkey wants to stop the PKK, an armed separatist group, getting stronger just as Turkey is trying to hammer out a peace deal that would end the group's dream of independence. 

Meanwhile, IS forces control much of Anbar Province in Iraq, immediately to Baghdad's west. There have been persistent reports of the group's fighters moving freely in Abu Ghraib, the first town to the west of the capital, and at the Baghdad International Airport, where a contingent of US advisers and US Apache attack helicopters are based. These US assets have been deployed in recent days to defend areas close to the capital. 

If Kobane falls, IS could be emboldened to advance further towards Baghdad, reasoning that US air power alone has proven insufficient to stop them. And the Iraqi military relied on to hold that ground, the same military that has turned tail and fled in front of IS advances in other parts of Iraq, may draw the same conclusion.