Turkey and the U.S. warned that a major Syrian border city was in imminent danger of falling to Islamic State, with the two countries putting the onus on the other to halt the extremist group’s advance.

Turkish President Recep Tayyip Erdogan pressed the U.S.-led coalition on Tuesday to move ahead with plans to arm and train Syrian and Iraqi ground forces to battle Islamic State, saying airstrikes alone weren’t enough.

An American military official said the U.S. believes the situation in the predominantly Kurdish city of Kobani is increasingly dire, and that the city is likely to fall shortly if Turkey doesn’t intervene. (More: Turkey Moves to Curb Protests Over Government Refusal to Intervene in Syria)

The complications for Turkey stemming from the advance on Kobani were mounting rapidly. Beyond U.S. pressure to step in, protests by the country’s restive Kurds were spreading quickly. At least a dozen people were killed in clashes with security forces in several Kurdish-majority cities, local media reported. The demonstrations reached Istanbul.

Airstrikes Tuesday by the coalition fighting Islamic State hit positions near Kobani, also known as Ayn al-Arab. But Kurdish officials and Syrian opposition members said the militants were still advancing against Syrian Kurdish fighters.