As Islamic State moves on the Kurdish city of Kobane, there are four reasons why Turkey must finally join the military action against the terrorist network, writes Benjamin Isakhan.

Late last week the Turkish parliament overwhelmingly voted in favour of military action against the terrorist network, the Islamic State (IS).

Despite some polls showing only 52 per cent of Turks support involvement in the US-led coalition against IS, the Turkish parliament took the bold move to permit the military to use force against IS in neighbouring countries and to allow allies to use Turkish bases to launch attacks against the militant jihadist group.

Since then, both president Recep Tayyip Erdogan and PM Ahmet Davutoglu have done a great deal of posturing but taken very little action. As the black flag of the IS death cult has been raised over the Kurdish city of Kobane in Syria, within eyesight of the Turkish border, the Turkish military has stood idly by.

The time has come for the Turkish government to make good on the parliament's authorisation. There are four fundamental reasons why Turkey must act now on Kobane.

First and foremost, Kobane is a humanitarian issue. It is not just a potential "strategic stronghold for IS", nor a "Kurdish hot-spot with links to the PKK", it is primarily a city occupied by human beings whose very existence is being threatened by radical and deadly jihadists.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 3 minutes 1 second 3 m 1 s Coalition air strikes on IS are 'useful but not enough', Kurdish fighters spokesperson says (Image: Reuters/Umit Bektas)

The IS track record reveals exactly what they will do in Kobane: impose strict Sharia law, seize weapons to fuel their campaign, publicly crucify those who disagree with them, gang rape and sell girls as sex slaves, and recruit child soldiers to fight on their behalf.

Turkey is in the best position to stop the slaughter of innocents and the expansion of IS. Turkey has a very well-trained and disciplined military - NATO's second largest - and right now scores of tanks and troops are stationed at the border near Kobane.

Failing to act on Kobane will not only lead to a mass humanitarian tragedy but will also put Turkey out of step with international sentiment on IS. This is a second key reason why Turkey must act now on Kobane.

Although the world has been slow (and at times reluctant) to respond, the momentum has finally swung against IS. The US has now cobbled together a broad coalition of more than 40 countries in its fight against IS - including crucially the Sunni-majority Arab states of Qatar, Saudi Arabia and the UAE, among others.

This unique coalition has come about in no small part because of the mass humanitarian tragedies that have faced various minority communities in the wake of the deadly IS advance, such as the Yazidis at Mount Sinjar, the Turkmen Shiites in Amerli or the Christians of Mosul.

The predominately Kurdish population of Kobane are no different.

This brings us to a third key reason why Turkey must act now on Kobane: the Kurds. Turkey has its own significant Kurdish minority population of some 15 million and there have long been tensions - including open hostilities - between Ankara and certain Kurdish groups such as the PKK.

With the US and others currently arming and training Kurdish groups in Iraq and Syria (let alone the prospect of Kurdish independence from those countries), Ankara is afraid that such groups will pass on their weapons and knowledge to the PKK and trigger renewed conflict.

While this seems a possible but unlikely prospect, we know for certain that inaction on Kobane will have a dramatic effect on Turkish-Kurdish relations. Indeed, Abdullah Ocalan, the jailed leader of the PKK, has threatened that the peace process would end immediately if Kobane were to fall to IS due to Turkish restraint.

We have already seen civil unrest in certain Kurdish parts of Turkey in response to the situation in Kobane. We will see much more if - via their inaction - the Turkish government make martyrs out of the small and isolated Kurdish community in Kobane. In the eyes of Kurds everywhere this would be proof enough that Turkey has no genuine interest in the plight of their people.

The fourth and final reason that Turkey must act now on Kobane, and perhaps that most central to Turkish interests, is that if allowed to develop its capacity and extend its territory, IS will wage attacks in and against Turkey.

By capturing Kobane IS would fortify and control a large wedge shaped piece of the Middle East that would stretch from Aleppo to Mosul, down almost to Baghdad (Ramadi and Fallujah) and back to Aleppo with the IS capital of Raqqa well and truly ensconced deep inside their territory.

This would be a major victory for IS but it is not their "end-game". If IS can hold and then extend their territory within Iraq and Syria, they will look elsewhere. While Lebanon, Jordan and others would make softer and perhaps more obvious targets, the 900 kilometre Syrian-Turkish border (1200km if you include Iraq) is relatively porous and difficult to defend - even by Turkey's strong military.

Let us not forget that IS has no respect for Turkey. They threaten the small Turkish enclave at the Tomb of Suleyman Shah - about 40 kilometres inside Syria. They have also fired countless mortars into Turkey from around Kobane.

But they have much more ambitious plans. Even a small symbolic attack inside Turkey with its proud tradition of democracy, inter-religious and inter-ethnic cohesion and its unique blend of the religious and the secular - would be a another major victory for IS.

Make no mistake, Turkey, the barbarians are at the gate.

Benjamin Isakhan is senior research fellow at Deakin University. He will give visiting lectures this week at Istanbul University and Bogazici University. View his full profile here.