ISIS is the given reason, the Kurds are the real reason. If the Kurds are targeted by the Turks then shame on us. They’ve been doing much of the fighting on our behalf for years.
They have been fighting on their own behalf. We have helped them with logistics, weapons, and intelligence to eradicate a common enemy, i.e., ISIS.
The Kurds have been seeking an independent state for decades. There are Kurds in Iraq, Iran, Syria, Armenia, and Turkey.
Not all Kurds are alike. The PKK is as nasty as they come, genuine Marxist-Leninists terrorists, the Kurdish equivalent of Antifa on steroids.