Many Turks initially blamed it on the Kurdish PKK, which was behind the previous Istanbul bombing earlier this month. But now Turkish officials have said that ISIS was behind this airport attack, which is much deadlier. It's also worth noting that Mustafa Kemal Ataturk (credited with being the founder of the Republic of Turkey) is the man responsible for transforming the Ottoman Empire into the modern secular nation-state of Turkey, so the ISIS attack against Ataturk Airport could be seen as an attack against Turkish secularism.