(CNN)Calling the situation in Syria's Eastern Ghouta "a travesty," US Ambassador to the United Nations Nikki Haley admonished the Russian government Tuesday for "deception, hypocrisy and brutality" on behalf of President Bashar al-Assad.
Nikki Haley berates Russia, UN colleagues over Syria: 'This should be a day of shame'
"I would ask my Security Council colleagues to consider whether we are wrong when we point to Russian and Iranian forces working alongside Assad as being responsible for this slaughter," said Haley, who further accused the Russian government of exploiting UN ceasefire negotiations to help Assad advance his campaign against opposition forces.
"Russia cynically negotiated a ceasefire it instantly defied," she said.
But Haley -- known for delivering blistering remarks at the council, particularly against Russia -- reserved some of her strongest admonitions for her UN colleagues, who she reprimanded for not holding Russia and Syria accountable with a tougher ceasefire agreement and stronger condemnations of Assad and his allies.
"This is a travesty," said Haley. "This should be a day of shame for every member of this council, and it should be a lesson about what happens when we focus on fleeting displays of unity, instead of on what's right. "
"History will not be kind when it judges the effectiveness of this council in relieving the suffering of the Syrian people," she noted.
The Security Council met Tuesday to consider the effectiveness of previous resolutions concerning Syria.
"The last few months have been some of the worst yet for many civilians inside Syria," the UN Under-Secretary-General for Humanitarian Affairs and Emergency Relief Coordinator Mark Lowcock reported to the council before Haley spoke, outlining the dire humanitarian situation in the Damascus suburb of Eastern Ghouta, one of the last significant rebel-held areas in the country.
The Syrian regime has conducted a sweeping campaign to flush rebel fighters from key parts of the country, including Eastern Ghouta, with the backing of their powerful ally Russia and its warplanes.
Last month, the Security Council adopted a ceasefire resolution to allow for the delivery of emergency aid and the evacuation of the wounded from some of Syria's hardest-hit areas, including Eastern Ghouta.
The diplomats said the United States fought to keep language in the resolution that called for an immediate start to the ceasefire and unfettered humanitarian access without delay. But the Russian delegation kept trying to water it down to delay implementation, the diplomats said.
The resolution that was ultimately adopted provided little detail on when the 30-day ceasefire was meant to begin, how it would be enforced or even whether all the parties concerned were aware of it.
In the weeks since the resolution was adopted, the UN estimates that over 1,700 people have been killed and thousands more have been injured in military operations in Eastern Ghouta.
Last week, hundreds of rebels evacuated the city after striking a deal for safe passage with the Syrian regime.
"Siege, starve, and surrender," said Haley. "This is the awful, unceasing rhythm of the Syrian war."
In his remarks, Russian Ambassador to the UN Vasily Nebenzya insisted Russia was the only council member taking steps to advance the ceasefire, and had provided for to the voluntary evacuations of civilians from Eastern Ghouta.
He further called on the United Nations to help rebuild areas he said were "liberated from terrorists" by the Syrian regime.