[81] A stalemate that had been in place for four years finally ended in July 2016, when Syrian government troops closed the rebels' last supply line into Aleppo with the support of Russian airstrikes.

[97] Hundreds of thousands of residents were displaced by the fighting and efforts to provide aid to civilians or facilitate evacuation were routinely disrupted by continued combat and mistrust between the opposing sides.

[126] Author Diana Darke has written that "The city has long been multi-cultural, a complex mix of Kurds, Iranians, Turkmen, Armenians and Circassians overlaid on an Arab base in which multi-denominational churches and mosques still share the space.

[131] On 16 February 2012, the UN General Assembly issued a resolution with a vote of 137 in favour, 12 against, and 17 abstentions, and called on Syria "to immediately put an end to all human rights violations and attacks against civilians.

This new approach led to the killing of at least one rebel commander following a dispute; fighters retreating with their loot caused the loss of a frontline position and the failure of an attack on a Kurdish neighborhood.

[167] Rebels over-ran several police stations and posts in the central and southern districts of Bab al-Nerab, Al-Miersa and Salhain, seizing a significant quantity of arms and ammunition.

[166] In December 2012, the al-Nusra Front unilaterally declared a no-fly zone and threatened to shoot down commercial aircraft, alleging that the government was using them to transport loyalist troops and military supplies.

However, according to an opposition activist, on 14 June the situation started reversing after rebels halted an armored reinforcement column from Aleppo that was heading for two Shiite villages northwest of the city.

[182] In early January, the rebels recaptured the Majbal (sawmills) area of al-Brej and captured the southern entrance of the stone quarries known as al-Misat, forcing government troops to retreat to the north.

[190] On 9 March, opposition forces launched an assault on Handarat, north of Aleppo, after reportedly noticing confusion in the ranks of Syrian government troops after the February fighting.

[198] Between 27–29 April, the FSA and Ahrar ash-Sham launched an operation in the old city of Aleppo and al-Hatab Square in the Al-Jdayde (Jdeideh) District, which included tunnel bombs[199] and the shelling of buildings where soldiers were stationed.

[209][210] In mid-October, ISIL captured four rebel-held villages northeast of Aleppo, while the Army seized the Syria-Turkey Free Trade Zone, the al-Ahdath juvenile prison and cement plant.

[215] In early February 2016, Syrian government forces and their allies broke a three-year rebel siege of two Shi'ite towns of Nubl and Zahraa, cutting off a main insurgent route to nearby Turkey.

[220] However, within days, the rebels launched a large-scale counterattack south of Aleppo, in an attempt to both open a new supply line into rebel-held parts of the city and cut-off the government-held side.

[247] The fall of Base 46, a large complex that reinforced and supplied government troops, was seen by experts as "a tactical turning point that may lead to a strategic shift" in the battle for Aleppo.

Tensions peaked in early April 2014, when a Syrian Republican Guard officer allegedly killed a Hezbollah commander during an argument over the opposition advance in al-Rashadin,[256] and other pro-government militia groups sent as reinforcements, such as the National Defence Force, proved to be unreliable in combat.

[273][272] With over four years of fighting, the Battle of Aleppo represents one of the longest sieges in modern warfare, which left at least 31,273 people dead,[76] almost a tenth of the overall Syrian war casualties at the time.

[274][275] The pro-opposition monitoring group the Syrian Observatory for Human Rights (SOHR) gave a similar number: it registered that 1,612 days of fighting for Aleppo left 21,452 civilians dead.

[112] Ravina Shamdasani, a spokesperson for the Office of the UN High Commissioner for Human Rights, issued a statement in November 2016 which said that "strikes against hospitals, schools, marketplaces, water facilities and bakeries are now commonplace, and may amount to war crimes".

It warned about the Syrian government use of imprecise explosive weapons on densely populated civilian areas, illustrating it with the example that eight barrel bomb attacks between January 2014 to March 2015 killed at least 188 civilians—while only one rebel was recorded among the fatalities.

[313] Following the recapture of parts of Aleppo by the Syrian government, the Office of the United Nations High Commissioner for Human Rights reported that a pro-government Iraqi Shi'ite paramilitary group[314] killed at least 82 civilians, including 11 women and 13 children, in the Bustan al-Qasr, al-Ferdous, al-Kallaseh, and al-Saleheen neighbourhoods on 12 and 13 December 2016.

[315] In January 2017, the Syrian Network for Human Rights (SNHR) and the Violations Documentation Center (VDC) submitted evidence of alleged war crimes committed by militias backed by Russia and Iran to the United Nations Commission of Inquiry on Syria.

[107] In March 2017, the UN Independent International Commission of Inquiry on the Syrian Arab Republic documented violations including chemical attacks and civilian executions perpetrated between 21 July and 22 December 2016.

[317] A UN envoy warned that rebels may have been committing war crimes in Aleppo by engaging in indiscriminate rocket warfare targeting civilians while trying to lift the siege in October and November 2016.

UN High Commissioner For Human Rights Zeid Ra'ad Al Hussein stated that their use was "totally unacceptable" and constituted indiscriminate attacks, as they were very difficult to aim correctly, frequently killing and maiming civilians in government-held areas.

[332] At the conclusion of the battle, Syrian state media claimed the Army had found the bodies of 21 executed civilians in rebel prisons, citing the head of Aleppo's forensic unit.

[341] Amnesty reported that, according to the Syrian Network for Human Rights, "at least 23 civilians were killed by YPG shelling and sniper attacks" in opposition-held areas in the city between February and April 2016.

[324] Time magazine wrote: ...the ongoing devastation inflicted on the country's stunning archaeological sites—bullet holes lodged in walls of its ancient Roman cities, the debris of Byzantine churches, early mosques and crusader fortresses—rob Syria of its best chance for a post-conflict economic boom based on tourism, which, until the conflict started 18 months ago, contributed 12% to the national income.

[345] On 2 October, Irena Bokova, the Director-General of UNESCO, expressed her "grave concern about possible damage to precious sites" and requested the combatants to "ensure the protection of the outstanding cultural legacy that Syria hosts on its soil".

[383] Rallies and demonstrations intended to show solidarity with Aleppo's besieged civilians, as well as protests against the Syrian government and its Iranian and Russian allies, were held in several cities across the world, organized by numerous groups.