The Syrian regime was in control of nearly all of Aleppo on Monday, the government and an opposition monitoring group said, as a proposal for the rebels’ safe passage from the city awaited approval from Russia, the regime’s main military backer.

Syrian state media said President Bashar al-Assad’s forces had captured 98% of the eastern areas of Aleppo that have been largely rebel-held since 2012. The rebels and the monitoring group, the Syrian Observatory for Human Rights, said regime forces were in control of 90%.

The fall of almost all opposition-controlled neighborhoods to government forces came as rebels were pushed Monday from the Sheikh Saeed neighborhood after days of intense ground combat with regime forces backed by Russian airstrikes and militias comprised of thousands of Shiite Muslim foreign fighters.

Opposition officials estimated that more than 100,000 civilians remained in the devastated rebel-controlled areas of the city, huddled in homes and basements or seeking shelter as regime and Russian warplanes carry out attacks.

The opposition acknowledged earlier this month that it was facing defeat in Aleppo, its last urban foothold in Syria. It has pushed for a truce that would allow rebel fighters and civilians to leave the city unharmed for areas of their choosing.

A plan put forth this weekend by the U.S., which backs some moderate Syrian rebel groups, would guarantee the fighters, their families and other civilians safe exit from the city to other parts of the country, mostly to areas of northern Aleppo province that remain under opposition control.

But rebels said Monday that Russia hadn’t approved the proposal.

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