Turkey’s Operation Euphrates Shield, which entered its 170th day Feb. 11 having seen the loss of 65 Turkish soldiers, is at its most critical juncture. In an operation launched the night of Feb. 7 from Aqil Hill, a dominating feature west of al-Bab, about 1,300 Turkish troops (700 commandos, 400 tank personnel and about 200 special forces) and nearly 2,000 Free Syrian Army (FSA) fighters took part. Thirteen Turkish soldiers were killed in the operation. Security sources told Al-Monitor that about 800 Islamic State (IS) militants and 10,000 civilians are still in the town center of al-Bab. IS uses these civilians as "live shields," and the Turkish army and the FSA now face tough urban warfare as they move toward the town center.As of noon Feb. 11, Turkish troops and the FSA had captured al-Bab silos, the al-Bab Sport Center in the west and the Zahra Mosque area in al-Bab's northwest. Turkish military sources said they have secured 25% of the town center and that heavy clashes are ongoing in the western and northern neighborhoods of al-Bab.