The series of terrorist attacks that have struck Turkey over the last year are sending the country — once viewed as a democratic, secular model for the Middle East — into a death spiral at the very moment when its people are to vote on a new constitution next month. Tourism — which had accounted for more than 10 percent of Turkey's GDP — is withering, and foreign direct investment is set to slow considerably. These outcomes will reinforce each other, producing a vicious cycle that will be difficult to halt.

Turkey's government-controlled media and large swaths of the population see the nefarious hand of the West in the country's unraveling. Observers often blame Turkey's deepening plight on its inability to reconcile traditional Islam and modernizing Western tendencies, as well as on external events, such as the conflict in Syria. But decisions by Turkish President Recep Tayyip Erdogan have also contributed to Turkey's vulnerability to terrorism.

Erdogan's first such decision, motivated by his desire to see Syria's Assad's regime collapse, was to allow fighters, including recruits for the Islamic State, to cross Turkey's southern border into Syria relatively freely. He failed to recognize fully the danger these fighters posed to Turkey's own security, particularly as many of them joined Islamist-affiliated groups that are as hostile to Turkey as they are to Assad.