The United Nations suspended its monitoring mission in Syria on Saturday because of the rapidly escalating violence there, leaving a U.N. peace plan for the country in tatters and raising fears that a slide into all-out civil war may be unavoidable.

The White House appealed to the government in Damascus to uphold its commitments under the plan even as the head of the U.N. mission in Syria announced that “significant risks” to the safety of team members meant they would no longer be monitoring its observance.

Calling the moment a “critical juncture,” White House spokesman Tommy Vietor said the United States has begun consulting with its allies “regarding next steps toward a Syrian-led political transition.”

“The sooner this transition takes place, the greater the chance of averting a lengthy and bloody sectarian civil war,” he said.

But with the international community paralyzed by indecision and deeply divided over how to address the complexities of the violence unfolding in strategically sensitive Syria, it was not immediately apparent what the next steps would be.

Maj. Gen. Robert Mood, a Norwegian who is chief of the observer mission, said the 300-strong team would reassess conditions daily and would resume operations “when we see the situation fit for us to carry out our mandated activities.”

His gloomy assessment seemed to hold out little hope that would happen soon, however. Citing the “intensification of armed violence across Syria over the past 10 days,” Mood said it was now clear that neither the government nor the opposition was interested in adhering to the cease-fire the observers were there to monitor.

“The lack of willingness by the parties to seek a peaceful transition, and the push towards advancing military positions, is increasing the losses on both sides: innocent civilians, men, women and children, are being killed every day,” Mood said in a statement issued in Damascus.

With no observers in the field to act as a check on excesses, and with fresh supplies of weapons flowing to rebel fighters and the government stepping up an offensive to crush opposition strongholds, the prognosis is for even greater bloodshed as the uprising against President Bashar al-Assad’s rule enters its 16th month, analysts said.

“On the ground, you’re going to see the regime and the opposition really going for each other,” said Andrew Tabler, a Syria expert with the Washington Institute for Near East Policy. “The gloves are going to come off, and this will drive up death tolls as the international community continues to look at the situation and tries to decide to what degree it wants to get involved or not.”

The mission’s mandate is still in place, and the monitors will remain in their hotels in Syria. Mood is due to brief U.N. Security Council members Monday ahead of an assessment on what steps need to be taken.

The monitoring mission was the last surviving thread of a six-point U.N. peace plan brokered by joint special envoy Kofi Annan that had already failed in its core purpose: the imposition of a cease-fire that would open the way for dialogue between the opposition and Assad’s government.

That it has become too dangerous for the monitors to continue working “is another nail in the coffin of the Annan plan,” said Randa Slim, a scholar at the Washington-based Middle East Institute. “It is dead because there is no constituency either on the government side or in the opposition to give up violence as a means of advancing their interests. Both sides are looking at this as an existential fight.”

The United States and its allies still hold out hope that a diplomatic solution to the crisis may be possible. The Syrian conflict is expected to dominate talks between President Obama and Russian President Vladimir Putin on the sidelines of a Group of 20 summit in Mexico on Monday, and U.S. officials have repeatedly said they believe Russia can be persuaded to step up pressure on Assad, Moscow’s chief Middle Eastern ally.

But the chill that has descended on U.S.-Russian relations in recent days following accusations by Washington that Moscow is arming Assad’s forces and
counter-accusations from Russia that the United States is arming the rebels have further dimmed prospects for consensus at the United Nations on tougher measures against the Syrian government.

Meanwhile, violence continued Saturday. Shells once again slammed into the embattled central Syrian city of Homs, a week after the government launched a stepped-up offensive to dislodge the rebels from neighborhoods under their control. At least 10 people were killed there and 28 died nationwide, according to the British-based Syrian Observatory for Human Rights.

Activist groups said at least 13 people were killed in the Damascus suburb of Saqba when government forces swarmed into the area alongside members of the irregular pro-government militias known as shabiha.