(CNN) - The United States has declared a United Nations effort to implement a ceasefire in Syria a failure and blamed Russia for stalling it, as the Syrian army continued to pound the devastated rebel-held enclave of eastern Ghouta.
Nikki Haley, the US ambassador to the UN, decried the pummeling of Ghouta and said Washington was "prepared to act" if the Security Council failed to demand an immediate, 30-day ceasefire.
Speaking at a meeting of the UN Security Council meeting on Monday, Haley questioned whether Moscow had the ability to influence the regime led by Syrian President Bashar al-Assad, after supporting his forces for years with an arsenal of weapons and fighter jets.
"Today we must ask whether Russia can no longer influence the Assad regime to stop the horrific destruction of hospitals, medical clinics, and ambulances. To stop dropping chemical weapons on villages," she said.
"Today, we know that the Russians did not keep their commitment. Today, we see their actions don't match those commitments, as bombs continue dropping on the children of eastern Ghouta," she said.
She said the US had drafted a new ceasefire proposal for Damascus and eastern Ghouta that had "no room for evasion." But there was no detail on when the Security Council might vote for the US proposal, or what the details of the draft were.
Haley also warned that the US would "act" against any nation that "is determined to impose its will through chemical attacks and inhuman suffering, most especially the outlaw Syrian regime," but did not elaborate. Last year, the US struck a Syrian air base after a chemical weapons attack on the rebel-held town of Khan Sheikhoun.
Eastern Ghouta split in three
On Monday activists on the ground in Eastern Ghouta, as well as state media, said that the Syrian regime and its allies have splintered the rebel-held enclave into three parts after the army intensified its onslaught in the region over the weekend.
Syrian regime forces advanced Sunday to cut off Douma, the largest city in Eastern Ghouta and the main rebel supply route, media activist Bilal Abu Salah told CNN.
The town of Harasta was also isolated from the rest of the enclave by regime forces, which additionally broke off several central and southern towns and villages in Eastern Ghota, he added.
Syrian state media reported on Sunday that "army units have completely cut off supply routes and movement lines of terrorist organizations between the northern and southern parts of Ghouta, which should accelerate the defeat of terrorists in the area."
1,000 children killed or injured
An agreement to evacuate the wounded in Eastern Ghouta was reached on Monday, according to a statement from rebel group Jaish al-Islam. The statement said that the agreement was reached with Russia through the mediation of the United Nations.
Abo Ammar Alwan, head of the political bureau of Jaish al-Islam in Eastern Ghouta, told CNN that on Monday no evacuations of wounded had taken place.
In the first two months of 2018, 1,000 children were reportedly killed or injured because of the conflict in Syria, UNICEF said Monday.
"The use of explosive weapons and indiscriminate attacks in densely populated areas have killed a growing number of children who now account for one quarter of civilian deaths. Over 360 children were injured in 2017, leaving many with disabilities," the statement read. "These are only the numbers that the United Nations was able to verify, and actual numbers are likely to be much higher."
Haley singled out the deaths of children in her criticism of the UN Security Council.
"If we can't act when children are dying, we have no business being here. If we can't save families that haven't seen the sun for weeks because they have been hiding underground to escape barrel bombs, then the Security Council is as impotent as its worst critics say it is," said Haley.
"The ceasefire has failed," she said. "We have drafted a new ceasefire resolution that provides no room for evasion. It is simple, straightforward, and binding."
No negotiations 'as long as bombing is an option'
Hadi al-Bahra, a negotiator for the Syrian opposition during the Geneva peace talks, told the Security Council that the Assad regime, not Russia, was in charge, and not ready to adhere to any international resolution.
"If you want negotiations to work, you must prevent the regime from relying on its military strategy. As long as bombing is an option, it will not negotiate," he said. The international community should be prepared to revisit sanctions against Damascus and its backers to help enforce UN resolutions. He also said member states should use the threat of military action for any further violations of a ceasefire. "It is feasible, it is necessary and it is overdue," he said.
Since launching its offensive against the enclave in mid-February, the Syrian regime has steadily been gaining territory, starting with villages and towns in the east.
Analysts believe it is now a matter of time before the regime takes control of the entire enclave, one of the last major rebel-held areas in the country, which is situated on the outskirts of Damascus.
The regime maintains that its offensive is against fighters affiliated with Jabhat al-Nusra, a former al-Qaeda affiliate that has rebranded itself several times and goes by several names -- whom it accuses of holding civilians against their will to use as human shields.
Armed rebel groups in the besieged enclave deny both accusations, saying al-Nusra's presence is limited and that civilians fear regime retaliation if they leave.