The leaders of Russia and Iran, military allies of Syria's president, talked Monday about joining forces to reach a quick political settlement in Syria, as the country's largest city, Aleppo, was poised to return to full government control.
Syrian state TV said it expected the evacuation of thousands of civilians and fighters from the last opposition footholds in Aleppo to be completed by early Tuesday.
The departure of the last rebels from Aleppo would close another chapter in Syria's civil war and would give President Bashar Assad a significant symbolic and strategic victory.
Almost six years after the outbreak of an armed rebellion against Assad, the Syrian leader will be in charge again of the country's five largest cities and the Mediterranean coast.
The presidents of Russia and Iran spoke by phone Monday to discuss the next moves. The Kremlin said Vladimir Putin and Hassan Rouhani "underlined the need for joint efforts to launch a real political process aimed at a quick settlement in Syria."
The leaders noted that a quick launch of talks between the Syrian government and the opposition in Kazakhstan's capital, Astana, would be an important step toward that goal, a Kremlin statement said.
The conversation came a day before a scheduled meeting of foreign and defense ministers of Russia, Turkey and Iran in Moscow. Russia and Iran have backed Assad, while Turkey has supported the opposition.
In the Turkish capital of Ankara, meanwhile, the Russian ambassador was shot and killed by a man shouting, "Don't forget Aleppo. Don't forget Syria!" The gunman fired at least eight shots, killing Ambassador Andrei Karlov, 62, at an embassy-sponsored exhibition, and was then shot dead by police.
At the United Nations, officials said more than 100 U.N. humanitarian staff on the ground in Syria, most of them Syrian nationals, could start monitoring the Aleppo evacuations. Earlier Monday, the U.N. Security Council had approved a resolution urging the immediate deployment of the monitors, following a French-Russian compromise over the text.
U.N. spokesman Stephane Dujarric said there will also be observers from the International Committee of the Red Cross and the Syrian Arab Crescent.
France said the monitors were needed to prevent "mass atrocities" from being committed by Syrian government forces, especially militias. But thousands have already been evacuated from the city and the operation could be completed before the observers arrive.
The resolution also demands that all parties allow unconditional and immediate access for the U.N. and its partners to deliver humanitarian aid and medical care, and "respect and protect all civilians across Aleppo and throughout Syria."
Syria's U.N. Ambassador, Bashar al-Ja'afari, claimed that one of the "main purposes" of the deployment was to rescue foreign intelligence officers from the former rebel-held area.
He named 12 alleged officers still trying to get out of Aleppo — six from Saudi Arabia and one each from Turkey, the United States, Israel, Qatar, Jordan and Morocco. He said: "We are going to catch them ... and show them to you."
The rebels captured eastern Aleppo in July 2012 and held on to it despite a ferocious assault in recent months by Syrian government forces, backed by Russia and a host of Shiite militias from Iraq, Lebanon, Iran and Afghanistan.
The evacuation of Aleppo began last week after Turkey and Russia brokered a cease-fire as government forces were closing in on the rebels' last redoubt, but has been repeatedly delayed.
The evacuation of more than 2,000 sick and wounded from the rebel- besieged Shiite villages of Foua and Kfarya was tacked onto the deal at the last minute. The opposition's Britain-based Syrian Observatory for Human Rights and the pan-Arab Al-Mayadeen TV said 10 buses left those villages with civilians on Monday.
There are also plans to evacuate hundreds of people from Madaya and Zabadani, two besieged, rebel-held villages near the Lebanese border. The Observatory and Mayadeen said 15 buses entered the two villages on Monday.
Rebel-held eastern Aleppo has been besieged for months, with several previous cease-fires breaking down and virtually no humanitarian aid reaching its tens of thousands of residents.
One of those who left Aleppo on Monday was Mohammed Abu Jaafar, who described a miserable five-kilometer (three-mile) trip that took more than two hours in an overcrowded government bus.
He said they passed three checkpoints, one manned by Russian troops, another by plainclothes Syrian intelligence agents and the third by Syrian troops.
Inside the bus, men, women and children were hungry and cold as they waited for hours in freezing temperatures, he said.
"Children were screaming, and some people fainted," he said, adding that there was no baby formula or diapers.
Among those evacuated Monday was 7-year-old Bana Alabed and her mother Fatemah, who tweeted about the horrors of living through the government's assault on eastern Aleppo, which destroyed much of the city. Their account had some 334,000 followers.
Speaking to the activist-run Qasioun News Agency in the Aleppo countryside, Fatemah said she was glad to have finally reached safety but expressed regret that she was forced out of her home city and said she did not want to become a refugee.
"I left my soul there," she said.
The Observatory and Turkey's Foreign Minister Mevlut Cavusoglu later said that since midnight Sunday, some 4,500 people have been evacuated from eastern Aleppo.
Reports differed on how many people remain in eastern Aleppo, but estimates converge around 15,000 civilians and 6,000 fighters.
Turkey's state-run Anadolu Agency said a total of 131 wounded people — including 46 children — were brought to Turkey for treatment since the evacuations began last week. The agency said five of them have since died.