Turkey says it has opened a refugee corridor into besieged Afrin, where the UN says after a week with no water the situation is acute. Turkey is striking heavily from the air and supporting Syrian Free Army units on the ground, facing stiff resistance as they begin day three of the assault on the Kurdish stonghold. The Turkish military has released aerial footage it says shows civilians being prevented from leaving Afrin. The military is also accusing the YPG forces of using civilians as human shields, and back in Ankara President Recep Tayyip Erdogan said he hoped the town would fall before the day's end. The YPG dismissed this claim as "unrealistic". After heavy street fighting the army says it has taken control of "critical areas" of the town, but has not provided details. Thousands of people have already been displaced and are effectively adrift in a war zone. Syrian military sources say Shi'ite militias loyal to Damascus have deployed alongside the YPG to resist the Turkish incursion.