Editor's Note: (Henri J. Barkey is the Director of the Middle East Program at the Woodrow Wilson Center. The views expressed are his own.)
Istanbul(CNN) Tuesday's bombing at Istanbul Ataturk Airport could not have come at a worse time for Turkey.
The attack, which early reports suggest has left at least 36 dead and dozens more injured, comes as the Turkish economy was already reeling after tourism plunged following attacks in Ankara and Istanbul.
Making matters worse was a decision by Russian President Vladimir Putin to advise Russians not to travel to Turkey following the downing of a Russian bomber.
But while the potential for further damage to the Turkish economy seems clear, what is less apparent is who actually is responsible.
Early reports -- and it must be stressed that these are only preliminary -- suggest that there were at least three perpetrators carrying automatic rifles who died after setting off suicide bombs.
It was an ambitious assault, and if early accounts are accurate, the death toll could have been even higher had it not been for officers who reportedly opened fire on the attackers in an effort to neutralize the threat.
The two most likely suspects are the Islamic State of Iraq and Syria (ISIS) and Kurdish insurgents. ISIS has increasingly targeted Turkey over the course of the last year, including perpetrating a number of suicide bombings.
The worst suspected ISIS attack came last October, when 103 civilians were killed in Ankara. Turkish Prime Minister Binali Yildirim said Tuesday that the early signs in this latest attack also pointed toward ISIS.
The other likely suspect in Tuesday's assault is the Kurdish Freedom Falcons or TAK, an offshoot of the Kurdish insurgent group the Kurdistan Workers' Party, or PKK, with which the Turkish state has been engaged in a bitter war since their peace negotiations collapsed in early 2015. TAK has allegedly perpetrated a number of attacks in Ankara and Istanbul on what it has claimed were "military" targets.
What makes things particularly complicated is that the People's Protection Units (YPG), the military offshoot of the PKK-affiliated Democratic Union Party (PYD), is actively fighting ISIS in Syria along with the United States.
The YPG has proven to be the single most effective force against ISIS, and has been involved in the operation against ISIS-controlled Manbij.
Manbij is critical because were it to fall, then ISIS's stronghold of Raqqa would be easier to capture.
Yet the United States and Turkey have been at odds over U.S. cooperation with the YPG because the group is affiliated with the PKK. And while the United States agrees with Turkey on the PKK, it distinguishes between the Syrian PYD and the Turkish PKK.
The truth is that both sides are right and wrong at the same time. The United States desperately needs the Syrian Kurds, but Turkey is anxious to delegitimize the PKK as it pursues a scorched earth policy against the PKK in the primarily Kurdish towns in the southeastern provinces of the country.
On balance, it seems far more likely that it is ISIS that perpetrated Tuesday's gruesome attack, which bears all the hallmarks of the ISIS assault on Brussels airport in March.
And it also makes sense strategically for the group as it would be punishing Turkey (which has reluctantly become more active in fighting ISIS networks in Turkey) while sowing doubt about the YPG. This in turn could increase the tension between Turkey and the Obama administration, weakening ISIS's main opponent in Syria.
One would assume that the PKK would not be foolish enough to perpetrate such an attack and jeopardize the YPG's relations with the United States when the Manbij operation is close to being concluded. But the truth is that the fog of terrorism is no different than the fog of war.
In the coming hours and days there will be much speculation and plenty of accusations bandied around. Like the fog of war, the fog of terrorism leaves many questions. But whoever is responsible, one thing is clear: Terrorism is another form of war, one that leaves civilians paying an extremely high price.
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