On 19 July 2012 anti-government rebels also invade the eastern districts of Aleppo dividing the city in half. The wealthier sections in the west remain faithful to the regime. One month later the Syrian armed forces launch the first offensive with air support.
Both sides are accused of violating international humanitarian law and of shelling civilian targets. An aerial bombardment by the government damages one of the most important pipelines for drinking water, rapidly causing water shortages throughout the city.
The rebels focus on airports and military bases of the government. Government forces are soon left with only one supply route to the city. Aleppo is expected to fall to the rebels very rapidly.
The violence also draws jihadi groups, such as al-Nusra, who mingle with the rebels. IS enters Aleppo too and quickly opposes the rebels: they attack mainly the armed opposition rather than the government forces
Syrian armed forces take advantage of the turmoil between IS and the rebels, breaking through the siege of West Aleppo and turning the tables by taking the east of the city under siege. Barrel bombs rain down on neighbourhoods in East Aleppo. According to reports from Amnesty International, 3,000 die in the barrel bomb attacks.
Conditions in East Aleppo rapidly deteriorate. The siege leaves inhabitants with virtually no access to healthcare or education. Three of the city’s four water systems are destroyed, and food prices soar. The World Health Organisation counts 1,000 new cases of cholera daily and declares an emergency. The shortage of care is severe: every hospital in East Aleppo was already bombed by the regime, some of them several times. Within four years, the life expectancy in Syria has dropped by 20 years.
Large numbers of refugees flee the city, others are trapped. In April Aleppo suffers the heaviest bombings since the start of the conflict. In 9 days the regime launches over 260 aerial attacks, 110 shelling incidents and 18 missile attacks. Sixty-eight barrel bombs are dropped on East Aleppo. In April the last paediatrician dies in East Aleppo, when his hospital is bombed. Neither the United States nor Russia intervenes in Aleppo during the bloodiest month ever.