Turkey's main interest in not joining an alliance to push back ISIS has to do with their long-standing opposition to their own Kurdish population, who they fear might obtain weapons or strength and renew their separatist ambitions.
Rather, Turkeys foreign minister, Mevlut Cavusoglu, warned on the state-run Anatolia news agency that weapons sent by Western countries to fight ISIS could end up in the hands of the Kurdistan Workers Party, or P.K.K., which Ankara considers a terrorist group.
We have expressed our concerns, Mr. Cavusoglu said. It may not be possible to control where these weapons will go.
Turkish officials raised concern about a host of issues surrounding the coalition, including the safety of 49 Turkish diplomats who have been taken hostage by ISIS, and whether the growing international effort to arm Kurdish fighters in Iraq against ISIS could embolden Kurdish militants in Turkey who have been seeking autonomy for the countrys largely Kurdish southeast. Turkish Kurds with the P.K.K. have fought with Kurdish pesh merga fighters in northern Iraq against ISIS. Turkey is also grappling with an influx of more than 800,000 Syrian refugees the largest Syrian refugee population after Lebanons.
http://www.nytimes.com/2014/09/09/world/europe/turkey-is-courted-by-us-to-help-fight-isis.html?_r=0
Look, the Turkish-Kurdish problem has been going on since the 1980s. There is no way they want to aid the Kurds across the border in Iraq, or risk that Turkish Kurds who have gone to fight with the peshmerga might come back with "ideas."