The Turkish border crossing of Oncupinar, an hour’s drive from the embattled Syrian city of Aleppo, is a chaotic buzz of people waiting to pass into one of the most violent regions in the world.

The U.S.-led coalition ramped up its aerial bombardment of Islamic State positions in the Syrian border town of Kobani on Thursday as the extremist group battled street by street with Kurdish forces and reportedly rushed in reinforcements from surrounding areas.

As U.S. generals and Secretary of State John Kerry warn that a strategic Syrian border town could fall to Islamic State militants, the Turkish military has deployed its tanks on its side of the frontier but only watched the slaughter.