The 300 observers serving with the U.N. Supervision Mission in Syria have been largely ineffective because of a lack of cooperation by the regime of President Bashar Assad, which is battling rebels in escalating violence throughout the country.
"We will try to work towards contributing to a political solution which would help alleviate all the suffering," Herve Ladsous, undersecretary-general for peacekeeping operations, said at a news conference in the Syrian capital.
"I have to hope that the whole process gains traction, that the vicious circle of violence can cease, that some political solution, and first and foremost, some political dialogue can get started," he said.
White House spokesman Jay Carney said Wednesday the defections of the Syrian ambassadors to Cyprus and the United Arab Emirates indicate the regime is crumbling.
"This is another indication, we believe, that senior officials around the Assad inner circle are fleeing the government because of the heinous actions taken by Assad against his own people, and the recognition that Assad's days are numbered," Carney told reporters.
The pullout leaves a reduced force of 150 U.N. military observers in Syria a week after the Security Council extended the force's mission for a month. UNSMIS observers, who entered Syria in April to monitor the peace plan put forth by U.N. and Arab League envoy Kofi Annan, recently suspended regular patrols because of the level of violence.
Wednesday, rebel leaders in Syria ordered followers to attack government troops heading to Aleppo while Turkey said it was closing its border crossings with Syria.
Meanwhile, opposition activists said at least 30 people were killed across Syria, CNN reported.
The Free Syrian Army official told CNN about 2,000 government troops, along with tanks and artillery were redeployed from Idlib to Aleppo, the commercial hub and largest city in Syria. Rebel forces are trying to seize control of Aleppo from government forces and, if successful, deal a blow to Assad's financial ties.
"There is random shelling of the eastern portion of the city as the Syrian army is trying to force out the [rebel Free Syrian Army]," an activist told CNN. "They are hitting civilian homes over and over."
Turkey's Customs and Trade Ministry said "all border gates with Syria will be closed Wednesday," Turkish state television reported. Thousands of Syrians have fled to Turkey to escape violence in their country that began as pro-democracy protests in March 2011.
The Local Coordination Committees of Syria opposition group said more than 16,000 people have been killed in the 16-month-long conflict. The Syrian government maintains "armed terrorist groups" are behind the violence in the country. The United Nations said this week nearly 17,000 people have died.