It's time for the international community to put pressure on rebel forces to leave Aleppo, says Lowy Institute Research Fellow Rodger Shanahan. As Syrian government forces and allies gain ground in the battle for Syria's largest city, more than 250,000 civilians are under siege in the remaining rebel-held territory. Now the tide is turning in favour of the pro-government forces, it's clear efforts by the rebel forces to break the siege have failed. The rebels' continued presence, embedded among civilians, is therefore serving no military purpose but is prompting Russian and Syrian government to pummel the city, Dr Shanahan says.

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