As the United States presses ahead with assembling an international coalition to “degrade and destroy” the Islamic State (IS), two potentially critical players are coming to the fore: the Kurdistan Workers Party (PKK) and its Syrian Kurdish franchise, the People’s Protection Units (YPG). Their ascent has been amply chronicled by Al-Monitor columnist Kadri Gursel and Al-Monitor contributor Mohamed A. Salih.

The PKK and YPG have proven to be the most effective forces in the battle against IS both in Iraq and in Syria, never so much as when they shepherded tens of thousands of Yazidi Kurds marooned on Mount Sinjar, in northwestern Iraq, to safety and helped Iraqi peshmerga retake the town of Makhmour.

The PKK and YPG are pro-secular, if quasi Marxist, in ideology. The latter has never targeted the West, and although the PKK has been fighting Turkey, a NATO member, on and off since 1984 for Kurdish self-rule, a cease-fire declared in March 2013 remains in effect. Moreover, both groups claim they are eager to cooperate with the West. So, what better local partners for the anti-jihadist alliance than them? This question is being pondered by European Union (EU) governments and US officials, senior Western officials speaking on condition of anonymity told Al-Monitor. All stressed, however, that for now the debate was, as one put it, "of a purely 'what if' nature."

“The problem is Turkey,” explained one of the officials, echoing concerns of a likely backlash from the Turkish government. Turkey branded the PKK as “terrorists,” and the label was adopted by the EU and Washington. The PKK is on both their lists of officially designated terrorist groups and has been accused of money laundering and drug trafficking. IS’ dizzying gains, however, have dramatically altered the security landscape across Syria and Iraq. “You’ve got to pick your poison. It's either [IS] or the PKK,” the same official stated.