— -- Russian and Syrian warplanes have halted strikes on the besieged Syrian city of Aleppo a day before a brief humanitarian pause is set to begin.

Russia has called on rebel fighters and civilians to use the brief 11-hour break in the bombing declared for Thursday to leave the rebel-controlled eastern side of the city.

But doubts have already been raised about the credibility of the brief pause. The U.N. said it needs more time to get relief aid to survivors and the U.S. has suggested the pause may be "too little, too late." Meanwhile, several residents of the besieged part of Aleppo say that leaving is not a real option and that they view the cease-fire as a media stunt.

The View From Inside a City in Ruins

"There is no sound of planes, but we can still hear shootings on the ground," Wissam Zarqa, a teacher in Aleppo’s al-Mashhad neighborhood, told ABC News. "The government is still trying to advance. As long as fighting and clashes are ongoing it is not possible for civilians to leave. Some elderly people who can’t keep living under siege might want to leave but they can’t because it’s not safe."

Even if he felt it was safe to leave, he would choose to stay, he said.

"We don’t feel like leaving our homes and becoming refugees," he said. "None of my friends are considering leaving."

Russia’s defense ministry, which announced the pause on Monday, said it would open two corridors for fighters and six more for civilians, adding that Syrian government troops had been ordered to pull back to allow fighters to pass. Russia has pledged to guarantee the safety of civilians leaving and that relief agencies will be allowed unfettered access to the city.

But the U.N. and aid agencies have said that the short window is not long enough to do what Moscow is suggesting.

A U.N. humanitarian spokesperson said that while it welcomed any pause in the violence around Aleppo, it wasn’t enough time for relief workers to reach people or to evacuate the wounded. U.N. officials said Russia had not coordinated with them on the pause, providing no warning before announcing it.

"We will use whatever pause we have to do whatever we can," Stephane Dujarric, a U.N. spokesman, told reporters in New York. "Obviously there is a need for a longer pause to get trucks in."

The international aid group, Doctors Without Borders, also said the pause was too short to evacuate the wounded safely.

Jens Laerke, a spokesman for the U.N.’s humanitarian agency OCHA, said that without guarantees for humanitarian workers’ safety, it would be impossible for them to enter.

Today, Russia’s defense ministry said it would extend the pause from eight to 11 hours, beginning it at 8 a.m. and ending it at 7 p.m. local time. The extension "will allow representatives of the United Nations and the Syrian Red Crescent to carry out all their operations to ensure the evacuation of the sick and wounded, and also to allow peaceful civilians out of the city," said ministry spokesman Sergei Rudskoi.

But U.N. spokespeople have already said they would need at least 48 hours for relief to reach people in the city.

Aid Groups Call Russia's Plan Insufficient

Several rebel groups have already rejected Russia’s proposal to withdraw out-of-hand, saying on Tuesday it would amount to a surrender. "The factions completely reject any exit -- this is surrender," Zakaria Malahifji, the political officer of an Aleppo-based rebel group told AFP. Al-Farouk Abu Bakr, an Aleppo commander in the powerful Islamist group Ahrar al-Sham, also told AFP the rebels would fight on.

Today Russia’s envoy to the U.N. in Geneva, Aleksei Borodavkin, condemned the rebels' refusal to leave and accused them of keeping civilians in the city as "human shields."

The pause comes as forces loyal to Syrian president Bashar al-Assad have been pressing a ground assault on the city.

The scene of intense fighting since July, Aleppo is now undergoing an a catastrophic humanitarian crisis, according to the U.N.

Intense bombardment from Russian and Syrian government planes has led to the destruction of hospitals, schools, roads and markets, severely affecting civilian access to water and electricity.

On Monday, 14 members of the same family, including eight children, were killed after their home was hit by an airstrike, according to activists in Aleppo and the White Helmets, a volunteer civil defense group that operates in rebel-held Syria. Humanitarian organizations have criticized the Syrian and Russian governments for the intense airstrikes and for reported use of chemical weapons and bunker-buster bombs, which can target people sheltering underground.

Some analysts believe the pause may actually be Russia's way of laying the groundwork for a more savage assault once it ends.

"This is Russia paving the way for the use of even more lethal force against Aleppo because it can claim that it gave civilians and moderates the chance to leave the city," said Firas Abi Ali, an Middle East analyst for HIS Country Risk. "Obviously, this takes no account of people who have nowhere else to go, and of moderates who do not want to surrender Aleppo to Assad. I expect more severe and indiscriminate bombardment after the cease-fire."

With the rebel areas encircled and under devastating bombing, most analysts believe it is only a matter of time before Aleppo finally falls to Assad. Western officials have said they have low hopes that Russia will return to a diplomatic solution before Aleppo is captured.

Talks on Aleppo -— declared defunct after the most recent cease-fire brokered between Russian and the U.S. evaporated at the end of September —- are underway again in Geneva, Switzerland. Following talks between U.S. Secretary of State John Kerry and his Russian counterpart Sergei Lavrov over the weekend, a U.S. delegation, along with rebel allies from the Gulf States, met with the Russians today again to agree on how to separate rebels from al-Qaeda-linked fighters.

Russia and the Assad regime argue the assault on Aleppo is justified by the presence of what they call terrorists there, including hundreds of fighters from the Nusra Front, which broke allegiance with al-Qaeda and changed its name to Jabhat Fateh al-Sham in July.

Earlier, the U.N. called for the 900 Nusra fighters it estimates to be in the city to leave. Nusra has rejected that offer, which other rebel groups also condemned as justifying Russia’s indiscriminate bombing.

Russia has now suggested its pause is in line with the earlier U.N. proposal to have Nusra withdraw.

On Wednesday, the U.N. special envoy to Syria, Staffan de Mistura appeared to back the plan again, saying the rebels' key sponsors should force them to evict Nusra.

"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," the U.N. special envoy for Syria, de Mistura, told Swedish daily Svenska Dagbladet. He said that suggestion would "take away any alleged justification, or alibi, for the heavy bombing of urban areas of eastern Aleppo."

Analysts have said rebels could push Nusra out, but are unwilling to do so while in a life-or-death struggle with the regime. Russia has previously disdained distinctions between moderate opposition groups and those deemed terrorists, giving rise to doubts whether Nusra’s removal—in any case unlikely—would mean a real cease-fire in Aleppo.

Saudi Arabia, one of the rebel’s chief sponsors, joined the Geneva talks today, but it was unclear if it would heed de Mistura -- on Monday warning it would intensify the supplies of heavy weapons to rebels unless Russia declared a full cease-fire.

U.S. and Russia Still at Odds

Outside the talks, the U.S. and the U.K. have also both voiced skepticism about the pause declared by Russia, suggesting it’s insufficient. Britain’s foreign secretary, Boris Johnson, rejected the Russian plan as not credible. "A durable and convincing ceasefire must be delivered by the Assad regime before any such proposal can conceivably be made to work," he said.

U.S. State Department spokesman Mark Toner said on Tuesday that a pause would "be a good thing" but that after months of "near-constant bombing" intended "to starve out and drive out the opposition and civilians," it was a "bit too little, too late."

Some observers have said they felt Russia was following a campaign-plan already employed in its own brutal war with Chechen separatists 16 years ago.

Then, Russia declared all of its rebel opponents jihadists and bandits, indiscriminately firing on areas held by them and levelling the Chechen capital of Grozny in the process of recapturing it, leaving virtually every building destroyed amid almost inconceivable devastation.

On Monday, the Russian embassy in Washington published a message on its official Twitter account, known for the undiplomatic style of its posts:

"#Grozny today is a peaceful, modern, and thriving city," it wrote. "Ain't that a solution we're all looking for? @JohnKerry?"