http://www.nytimes.com/1991/04/15/world/new-reports-say-1980...

https://www.counterpunch.org/2014/07/11/the-october-surprise...

Though the Kurds are almost everything the US could want in a mideast ally - moderate, self-sustaining and stable, demonstrably capable - we will probably never embrace them fully due to our relationship with Turkey.

Some backstory:

Turkey lists the PKK as a terrorist organization, as Ankara and PKK have been fighting a separatist conflict for decades. Though the PKK has never targeted Americans, the US still lists the PKK as a terror org to placate Ankara.

The US has invested in Turkey as a strategic regional ally since the Cold War. Geographically Turkey was a key bulwark against Soviet power, and indeed we housed nuclear missiles within Turkish territory for many years. Even after the USSR collapsed, Turkey's regional value to the United States has grown. Incirlik is one of the largest air bases in the world, and remains a key logistical point for our military action in Afghanistan and Iraq.

Turkey was also important to the US ideologically because they were a stable, moderate, secular Muslim state, e.g. the kind of country we wanted to serve as a template for the rest of the Middle East. Thanks to Erdogan, this value has decreased sharply thanks to his moves to consolidate autocratic power at the expense of the still largely secular and moderate Turkish populace.

(Tried to keep the value judgements out of that, sorry if I offended someone by summarizing too generally).

If that doesn't make them a terrorist organization... well, I don't know what to tell you.

It's a war.