The defections of Syrian ambassadors to both the United Arab Emirates and Cyprus are another indication that senior officials around the Assad inner circle are fleeing the government because of the heinous actions taken by Syrian President Bashar al-Assad against his own people, "and the recognition that Assad's days are numbered," White House press secretary Jay Carney said on Wednesday.

Remarking on the continuing assault in Aleppo, Syria's largest city, Carney said, "The Assad government is reportedly using not just helicopters, but fixed-wing aircraft as well as tanks to perpetrate heinous violence against the Syrian people and unarmed civilians. We condemn that." It is another indication of the "depths of depravity" that Assad has demonstrated himself capable of achieving, Carney said during a briefing aboard Air Force One as President Barack Obama flew from a campaign event in Seattle to one in New Orleans.

The United States and its partners will continue to take steps to isolate the Assad regime, "to starve it of financial resources through sanctions, which makes it increasingly difficult for Assad to finance his brutal crackdown on his own people," Carney said.

"We continue to support the opposition's efforts to consolidate itself and to take steps to implement their broad agreement in Cairo over what a political transition would look like," he added.

Asked if the announcement by the Russian foreign minister, that Russia would regard the use of chemical weapons by the Syrian government as unacceptable, indicates Russian support for Assad may be softening, Carney said.

"We certainly agree that any use of chemical weapons is unacceptable, and anyone responsible for the use of chemical weapons will be held accountable by the international community." "We continue to be concerned about the disposition of the Assad regime's chemical weapons," he said. "We believe that they are still under the control of the government, and we use every opportunity to remind the Syrian government that it must maintain control of those weapons and, of course, never use them." As for Russia, Carney said U.S. officials are in regular consultations with the Russians as well as others about the need to form an international consensus around the notion that Assad must go in order for there to be hope for a peaceful transition in Syria.

"The longer Assad remains in power, the more deadly the situation becomes in Syria," he said. "As we have seen in Aleppo today, the longer we go, the more willing Assad is to take extreme measures to kill his own people."