Well hopefully novi comes along to shed light on why the various factions involved haven't taken decisive action
Mostly I'm curious if he or anyone has an idea of what Turkey and Israel's angles are. But decisive action isn't really a trademark of the middle east. Their trademark is more along the game of thrones line.
Turkey’s take:
Turkey’s policy has shifted gradually over time. Originally they were aligned against the northern Kurdish militias in northern Iraq due to their connections to the PKK (the Kurdish Worker’s Party) based in eastern Turkey. They even sent troops across the border into northern Iraq to attack PKK bases during our invasion and occupation of the country. Since then, the resurgence of Al Qaeda in Iraq (what is now ISIS or just IS) in both Iraq and Syria has increased security concerns in Turkey.
The ISIS is a concern yes, but Turkey’s major target of concern is northern Kurdish groups in Syria, principally the PYD (Democratic Union Party), which is a stronger supporter of the PKK. They became a vitally increased threat when Assad gave them control of border crossings with Turkey in retaliation for Turkey’s support for rebels.
In order to address the threat of the PYD Turkey funded al Nusra, which became an unsustainable tactic for them because 1.) Al Nusra was losing ground to the ISIS, and 2.) The United States put a lot of pressure on Turkey to pull their funding of the Al Qaeda affiliate which Turkey has now labeled, after much prodding, a terrorist organization. Their other plan of action though was to support northern Iraqi Kurds in the hopes of diminishing the influence and power of the PYD with the larger Kurdish National Council.
That didn’t turn out so well for Turkey though. The Kurdish Regional Government of Iraq didn’t have the means to influence the PYD in the way that Turkey had been hoping for; thus Turkey is currently engaged in under the table talks with the PYD due to the increasing threat that the ISIS poses. In the meantime the relationship fostered with the Northern Iraqi Kurds has blossomed into a mutually beneficial economic and political one.
1.) It gives Turkey some influence within a state dominated now by the ISIS and Shia, and 2.) It represents a safer region for Turkey (and Israel now) to import oil from Iraq through a newly build oil pipeline. The sustainability of it all though is dependent on Turkey’s continued negotiations with the PKK of course, though the economic reliance on Turkey likely makes the KRG less eager to support the PKK as heavily as they have in the past.
Israel is a little more opaque and I think they are mostly concerned about their borders, which would make the invasion of Jordan by the ISIS a red line for them and which makes them especially attentive to their border with Syria.