Obama, Turkish president speak after Istanbul airport attack

President Obama spoke with Turkish President Recep Tayyip Erdogan early Wednesday following a terrorist attack at Istanbul’s international airport.

{mosads}Obama expressed his condolences to Erdogan and pledged U.S. assistance to the Turkish-led investigation, White House press secretary Josh Earnest told reporters aboard Air Force One.

Three attackers opened fire and set off suicide bombs at Istanbul’s Ataturk International Airport on Tuesday night, killing at least 40 people and wounding more than 200.

It’s not yet clear who is responsible for the attack. Turkey is a member of the U.S.-led coalition fighting the Islamic State in Iraq and Syria (ISIS) and, as a result, has faced an uptick in violence from the extremist group.

Turkish and U.S. officials have suggested that ISIS or an ISIS-linked group could be responsible, pointing out the tactics and target were similar to a strike on the Brussels airport in March. ISIS claimed responsibility for that attack.

But Turkey has also been battling Kurdish insurgency for the better part of a year. A Kurdish separatist set off a car bomb in Ankara, Turkey’s capital city, in March, killing 37 people and injuring more than 100.