People inspect the damage at the Medecins Sans Frontieres-backed Al-Quds hospital after it was hit by airstrikes, in a rebel-held area of Syria's Aleppo, April 28, 2016. Reuters Forces loyal to Syrian President Bashar Assad pounded the Syrian city of Aleppo in airstrikes on Thursday, targeting a hospital and killing at least 55 civilians in a new offensive that's believed to have been months in the making.

The situation has resulted in a "catastrophic deterioration in Aleppo over the last 24 to 48 hours," Jan Egeland, the chairman of the UN humanitarian task force for Syria, told reporters Thursday.

"Doctors have been killed, health workers have been killed, and medical workers have been blocked from coming to their patients," he said. "We can now refute allegations we heard from some government people and others that there are only fighters and terrorists in Daraya. We have seen with own eyes very many children, very many other civilians."

Local truces were brokered near Damascus on Friday, but there was no mention of halting combat in Aleppo, further north.

Both Moscow and Damascus have denied that their warplanes were responsible for airstrikes on Al-Quds hospital — a facility supported by Doctors Without Borders — and continue to insist that they are only striking terrorists. US Secretary of State John Kerry called it a "deliberate strike," one that "follows the Assad regime's appalling record of striking such facilities and first responders."

But the Assad regime considers all rebels to be terrorists, making medical facilities in opposition-held territory "de-facto illegal" and therefore legitimate targets, according to The Guardian.

A woman who survived an airstrike sits amid the damage in the rebel held area of Old Aleppo, Syria, April 28, 2016. Abdalrhman Ismail/Reuters Many analysts argue that the cessation of hostilities (CoH) brokered by the US and Russia in February has legitimized Russia and Assad's unwillingness to differentiate between Islamic extremists and more moderate, Western-backed opposition groups. The truce, they say, has allowed forces loyal to Assad to keep bombing rebel territory, as long as they can argue that terrorist organizations such as ISIS and Jabhat al-Nusra are present.

As such, many are questioning the extent to which the agreement gave Assad and his allies cover to plan their onslaught on Aleppo.

"I was told back in February that a full Aleppo offensive would take 2-3 months to prepare," The Washington Post's Beirut bureau chief Liz Sly tweeted on Thursday. "So the CoH just filled the gap."

Civil defense members help their injured comrade after airstrikes in the rebel held area of old Aleppo. Abdalrhman Ismail/Reuters

'The administration is now giving full cover to the Russians'

So far, Washington's response to the onslaught in Aleppo has been limited t0 official statements condemning the airstrikes that destroyed Al-Quds hospital. And most say it will stay that way.

"If the US doesn't have a plan to roll out just after official end of CoH (and Obama's comments suggest it), the perception of collusion [between Russia and the US] will grow," saidEmile Hokayem, a Middle East analyst at the International Institute for Strategic Studies.

Hokayem was likely referring to comments Obama made in a press conference from London last week, where, in reference to the CoH, he said "we are going to have to play this option out."

"If, in fact, the cessation falls apart, we’ll try to put it back together again even as we continue to go after ISIL," he said, using an acronym for the Islamic State terrorist group. "And it’s my belief that ultimately Russia will recognize that."

A man reacts at a site hit by airstrikes in the rebel-held area of Al-Kalaseh neighborhood of Aleppo. Abdalrhman Ismail/Reuters But both the Defense Department and Kerry have begun using a new line that appears to validate Russia's continued attacks on Aleppo in the midst of the truce.

Tony Badran, a research fellow at the Foundation for Defense of Democracies, put it bluntly: "The administration is now giving full cover to the Russians."

When asked last week whether the Russian airstrikes on Aleppo meant that Moscow was preparing to end the agreement, US Army Col. Steve Warren, the spokesman for Operation Inherent Resolve in Iraq, responded that it was "complicated." He said that was because Jabhat al-Nusra, the Syrian Al Qaeda affiliate, "holds Aleppo" and is not party to the agreement.

Some analysts, including Hokayem, wondered whether Warren had misspoken. While Nusra has indeed been building up its presence in Aleppo since February, the city is also occupied by civilians and armed opposition groups associated with the US-backed Free Syrian Army that agreed to abide by the fragile agreement.

"Al-Qaeda’s affiliate Jabhat al-Nusra does not 'hold' Aleppo, but has a comparatively small force, dwarfed by the mainstream opposition," Syria expert Charles Lister pointed out shortly thereafter.

People inspect the damage at a site hit by airstrikes, in the rebel-held area of Aleppo's Bustan Al-Qasr, Syria April 28, 2016. Reuters But Kerry repeated the line in a later interview with The New York Times editorial board, saying Russia's military buildup around the city was primarily aimed at weakening Nusra's presence there.

He added: “We are not going to sit there and let [Putin] do his thing supporting the regime and hammer at the opposition and say, 'This is working,'" he said. "Obviously, we’re not stupid about it."

But Badran believes that Washington's desire to stay out of the war will compel US officials to keep colluding with Russia in the negotiating room while turning a blind eye to its aggression on the ground.

"The White House was always deliberately leveraging Russian military operations against the opposition, translating it into political concessions" for the regime, Badran told Business Insider on Thursday. Kerry made that clear in February, Badran added, when he blamed the collapse of the first round of peace talks in Geneva on the opposition.

Kerry said, "'Don’t blame me – go and blame your opposition,'" a Syrian aid worker told Middle East Eye at the time. According to the publication, Kerry also told the aid workers that the rebels who left the talks were essentially paving the way for a joint offensive by Assad and Russia that would "decimate" the opposition.

That statement, Badran says, was not difficult to interpret.

He said: "Kerry was essentially telling the opposition: 'The United States won’t lift a finger to help you fend off the Russians.' It behooves you, then, to accept what is being offered right now, because your position will only get worse."