The United Nations special envoy to Syria, Staffan De Mistura, has made an impassioned plea to try to stop the fighting in Aleppo.
He is offering to personally accompany fighters from the Fateh al-Sham group, previously known as the al-Nusra Front, out of the city so aid can reach trapped civilians.
The presence of the fighters in Aleppo and across Syria has been used as a justification for the Syrian government and Russia to continue their offensive in Aleppo.
Mr de Mistura says he is prepared to put himself in harm's way to stop the fighting, addressing the rebels directly:
"And if you did decide to leave, in dignity, and with your weapons, to Idlib or anywhere you wanted to go, I personally am ready, physically, to accompany you."
The rebel-held east of Aleppo has been devastated by a Russian-backed government offensive.
The offensive has included multiple air attacks on hospitals, with hundreds of civilians killed and thousands wounded.
Mr De Mistura says, if fighting continues, the city could be completely demolished by Christmas.
"The bottom line is, in maximum, two months, 2.5 months, the city of eastern Aleppo, at this rate, may be totally destroyed."
And he says history will judge Syria and Russia if they use the presence of about 900 rebels fighters as what he calls an "easy alibi" for destroying the besieged area.
He points out it is still home to 275,000 citizens, including 100,000 children.
"We will all remember that there was a possibility and an option for avoiding destroying a whole city for the sake of aiming at 1,000 people who are considered terrorists and using that as an alibi, perhaps, for destroying a whole city."
Syrian president Bashar al-Assad has denied reports his government is targeting hospitals and civilian infrastructure.
Mr Assad says individuals sometimes commit mistakes in any war but, if his government had been committing atrocities, he could not have remained president.
"If I'm the problem, if I'm the reason of the war, I would leave. But it's not about me. I'm just used as a nominal reason. It's much bigger than that. It's about Syria, it's about the government, it's about independence, it's about the war on the regional level, it's about the war between the great powers."
Meanwhile, the Russian military has issued a dire warning to the United States against striking the Syrian army.
Russian Defence Ministry spokesman Igor Konashenkov says any US strikes on areas controlled by the Syrian government could jeopardise the lives of Russian servicemen.
And he says Russia's air defence weapons in Syria stand ready to fend off any attack.
"Besides, I will remind the US colleagues that the air defence of the Russian military bases is covered by a range of Russia's S300 and S400 air defence missile systems, which cover a radius that may be a surprise to any country operating its aircraft over the country."
