Aleppo's Brief Cease-Fire Extended Amid Fears of New Russian Offensive

— -- Russian President Vladimir Putin today extended a brief "humanitarian pause" in fighting around the besieged city of Aleppo, Syria, by adding another 24 hours to the initial 11-hour break in fighting, Russia's military said. The U.N. said Russia has promised to further lengthen the cease-fire by another four days, although that has yet to be confirmed by Russia.

A rare sense of quiet today in Aleppo is meanwhile fraught by concerns that Russian and Syrian government forces will launch a new offensive once the temporary cease-fire ends. Feeding the fears are signs that Russia is preparing a major assault and using the break only to cover itself against any accusations that it showed insufficient concern for civilians.

A Russian naval fleet, accompanying the country’s only aircraft carrier, is currently steaming toward Syria in what observers says is Moscow’s largest naval deployment since the Cold War. A senior NATO diplomat told Reuters they believed the buildup is intended for a final assault on Aleppo within the next two weeks.

Russian and Syrian officials have suggested that after the cease-fire the Syrian army will clear Aleppo of the forces fighting the government of Syrian President Bashar Al-Assad. “After the humanitarian pause, the clearing operation begins,” Franz Klintsevich, a senior member of Russia’s parliamentary defense committee told Russia’s chief state paper, Izvestia today.

German leader Angela Merkel pressed anew for the brief halts in fighting to become a full-fledged cease-fire: “There must be work as soon as possible on achieving a cease-fire,” Merkel said at a European Union summit in Brussels. “Not just one over several hours per day, followed by many hours of bombing, but a lasting cease-fire."

U.N. Secretary-General Ban Ki-moon echoed that, saying while the halt in bombing was welcome, it was "the bare minimum" that needed to be done.

For today at least there were none of the Russian and Syrian government airstrikes that have terrorized rebel-held areas in Aleppo in recent weeks. Syrian state media reported that corridors had opened to allow people to exit. And residents of the city said that the government was dropping leaflets urging them to leave.

“There are no warplanes, but we have been hearing the sound of a helicopter that has dropped leaflets from the government,” Mohamed Abu Rajab, a radiologist in Aleppo, told ABC News. He said he is hoping that patients in need of urgent medical care can be evacuated from Aleppo during the cease-fire.

“We are looking into evacuating the wounded and preparing a list of people who have serious injuries that we can’t treat inside, but so far no one has left,” he said.

Fewer than 30 doctors are left in Aleppo, according to the U.N, and only about five hospitals are left functional after others have been destroyed by airstrikes.

Russian President Vladimir Putin initially agreed to an 11-hour “humanitarian pause” in fighting to allow supplies to reach the estimated 250,000 people still living in the city.

A United Nations humanitarian adviser, Jan Egeland, said Russia has agreed to extend the pause and that the U.N. now had a “window from at least Friday till Monday” and is pushing for longer.

But Russia would not confirm that the cease-fire would go beyond 24 hours. Putin spokesman Dmitry Peskov warned reporters that any extension may be cut short if Syrian rebel forces appeared to be regrouping.

Rebel fighters and civilians in Aleppo meanwhile remained deeply skeptical about the pause with little sign today that many are heeding the calls to leave. After the past two weeks of Russian and Syrian airstrikes killing hundreds and targeting hospitals, schools and bakeries, some Aleppo call the cease-fire a “media stunt” and psychological tactic meant to force rebels' surrender.

Some mainstream rebel groups as well as a powerful jihadist organization have rejected the call to withdraw. The jihadist group, Fateh al-Sham, the al-Qaeda affiliate previously known as Jabhat al-Nusra, said in a statement to the BBC that it would fight on, pointing out previous occasions where rebels have been starved and bombed into surrendering.

As the cease-fire began this morning, clashes erupted around one of the opened corridors by which people could leave. Small arm and artillery fire was exchanged around a crossing in Bustan al-Qasr, one of two corridors offered as a way for fighters to exit.

“I was in Bustan al-Qasr this morning and there were clashes,” Wissam Zarqa, a teacher who lives in al-Mashhad in the besieged part of Aleppo, told ABC News. He said the government and the Free Syrian Army were fighting in the area.

Zarqa said he does not want to leave his home and become a refugee and that he also doesn’t believe that leaving is safe, as the Syrian government claims. He said he had heard the government encourage people to cross the front lines and go back to “the lap of the homeland.”

ABC News has seen photos of leaflets locals say were dropped by the government. One shows a photo of a green bus that supposedly will take people out of the besieged area. Another photo on the same leaflet shows a man with what appears to be a head injury lying on the ground with the words “this will be the end” printed on top. Another says the safety of people who decide to leave is guaranteed.

Meanwhile, the Russian carrier group sailing toward Syria is apparently headed to reinforce Russia’s air campaign in Syria. A senior NATO diplomat told Reuters that the exceptional deployment suggested Russia was preparing to use it in a coup-de-grace as it launches a final assault on the city: "This is not a friendly port call,” the diplomat said. “In two weeks, we will see a crescendo of air attacks on Aleppo as part of Russia's strategy to declare victory there.”

That likelihood seemed to be echoed by the Russian defense committee official, Klintsevich. “After the pause, the clearing operation starts. But it will be difficult for anyone to say Russia is not concerned about the interests of the civilian population,” he told Izvestia.

Despite the grave signs, the pause has been accompanied by stirrings of new diplomatic talks. A U.S. delegation met with Russian officials in Geneva to discuss how the two sides might agree on how to separate terrorist groups from the rebel opposition in Syria

Russia says the assault on Aleppo is justified by the presence of Jabhat al-Nusra, the al-Qaeda branch that recently rebranded as Fateh al-Sham. The U.N. has called for the around 900 Nusra fighters it estimates to be in the city to leave.

Rebels and activists have criticized that as accepting Russia’s indiscriminate bombing as legitimate. But the U.N. mediator for Syria, Staffan de Mistura, appeared to push for the Russian plan, saying that nations backing Syria's rebels could apply pressure to have Nusra forced out of Aleppo.

“Important countries, like Saudi Arabia, Turkey and Qatar, which have influence over the mainstream rebel groups, are in a position to suggest to those groups to tell the al-Nusra fighters that it is time to go to Idlib,” de Mistura told the Swedish daily Svenska Dagbladet. That would “take away any alleged justification, or alibi, for the heavy bombing of urban areas of eastern Aleppo.” Mistura said.

Analysts have said rebels could push Nusra out of Aleppo, but will not while engaged in a life-or-death battle with the regime.

Russia has implied it will halt the attack on Aleppo if Nusra can be removed. In practice Russia officials have rarely drawn a distinction between it and other rebel groups. Russian foreign ministry officials publicly only refer to the moderate opposition in quotation marks.

But following a meeting between U.S. Secretary of State John Kerry and his Russian counterpart Sergey Lavrov over the weekend, the U.S. is now probing Moscow on this issue again.

“I urge Russia to sit at this table in Geneva and be serious about finding a simple way, which we are offering, to make sure that those who are genuinely terrorists are in fact separated out, isolated," Kerry said on Wednesday night.