Updated at 11:35 a.m. ET
(CBS/AP) PARIS - The United States and its international allies called Friday for new, global sanctions against President Bashar Assad's regime, stepping up the pressure after the defection of a top general dealt a major blow to the Syrian leader.
The question, explains CBS News State Department correspondent Margaret Brennan, is whether Russia and China will finally and completely sever the financial lifeline which is keeping Assad in power. Secretary of State Hillary Rodham Clinton has said they've essentially given Assad a free pass by failing to implement sanctions and continuing to import Syrian oil.
Washington urged countries around the world to demand that the two nations force Assad to step down.
Meanwhile, Syrian Brig. Gen. Manaf Tlass, a member of the elite Republican Guards and a son of a former defense minister, abandoned Assad's regime, according to Western officials. It was the highest profile departure in 16 months of bloodshed that activists say has killed more than 14,000 people.
The uprising in Syria began in March 2011 with peaceful protests calling for Assad's ouster but has become increasingly militarized as the opposition took up arms to fight a brutal government crackdown. Military defections also have been on the rise.
French Foreign Minister Laurent Fabius said Tlass had defected and was en route to France, where he has a sister and where world diplomats met Friday to bolster the Syrian opposition. Later, Fabius backtracked, saying he was not sure of Tlass' final destination.
The U.S. Defense Department confirmed that Tlass had defected and was heading to Turkey, CBS News national security correspondent David Martin reports. Pentagon spokesman John Kirby called his defection "a crack in the inner circle" for Assad.
Clinton hailed the defection of top military officials in Assad's inner circle, telling reporters that "regime insiders and the military establishment are starting to vote with their feet."
She said this shows that "those with the closest knowledge of Assad's actions and crimes are moving away. We think that's a very promising development. It also raises questions for those remaining in Damascus, who are still supporting this regime."
A member of Syria's opposition National Council, Hassem Hashimi, described Tlass as a powerful figure in the Assad regime. "The defection of Tlass will encourage a lot of similar people to defect as well," he told The Associated Press in Paris.
Clinton joined senior officials from about 100 other countries in Paris to win wider support for a Syrian transition plan unveiled last week by U.N. mediator Kofi Annan. Joined by America's allies, she called for "real and immediate consequences for non-compliance, including sanctions," against the Assad regime.
But with neither Moscow nor Beijing in attendance, much remained dependent on persuading the two reluctant U.N. veto-wielding powers to force Assad into abiding by a cease-fire and the transition strategy. Clinton urged governments around the world to direct their pressure toward Russia and China as well.
"What can every nation and group represented here do?" Clinton asked. "I ask you to reach out to Russia and China, and to not only urge but demand that they get off the sidelines and begin to support the legitimate aspirations of the Syrian people."
"I don't think Russia and China believe they are paying any price at all nothing at all for standing up on behalf of the Assad regime," she added. "The only way that will change is if every nation represented here directly and urgently makes it clear that Russia and China will pay a price. Because they are holding up progress, blockading it. That is no longer tolerable."
Britain's foreign secretary, William Hague, said, "We don't rule out any option for the future because it is deteriorating. It is a very grave situation. It is a murdering regime, so we want to see a peaceful transition. But we are not ruling anything out."
Diplomats urged the fractured Syrian opposition to unite.
Several rounds of international sanctions so far have done little to stop the bloodshed. This time the United States is hoping for sanctions that have more of an impact.
But Syrian rebels say sanctions aren't working and want quick military action. New violence in Syria led many activists to dismiss the importance of the Paris meeting. Anti-regime activists say Syrian forces have killed at least 25 people, arrested scores more and torched dozens of homes while seizing the northern city of Khan Sheikhoun from rebels.
At the Paris conference, opposition member Hashimi called for a no-fly zone to prevent military forces from "flying over defected soldiers and civilians and bombarding them."
"We're sick of meetings and deadlines. We want action on the ground," said activist Osama Kayal, speaking via Skype from an area near Khan Sheikhoun.
In Paris, Burhan Ghalioun, former leader of the Syrian National Council, explained his frustration after the conference.
"I am not satisfied at all because the Syrians are not waiting for press communiques. What preoccupies the Syrians today is the way we can stop the massacre. Every day there are 100, 130, 150 victims and the people only think about that," he said. "They want action, they want measures and practical mechanism to stop the killings."
Any international mandate for military intervention would almost certainly be blocked by Russia and Moscow in the U.N. Security Council.
U.S. officials say a U.N. resolution could be introduced next week, but one that only seeks further economic pressure on Assad's government. Even the chances for that action are unclear, with Russia and China effectively watering down Annan's blueprint for transition at a conference in Geneva last weekend. That plan granted both Assad and the opposition veto over any interim government candidate they oppose.
The opposition expressed some optimism about the defection of Tlass, who was one of the most important Sunni figures in Syria's Alawite-dominated regime.
As the son of longtime Defense Minister Mustafa Tlass, he was a member of the Syrian Baath Party aristocracy, part of a privileged class that flourished under the Assad dynasty.
His father and Assad's father, Hafez, had been close friends since their days in the Syrian military academy in Homs and became even closer after being posted to Cairo in the late 1950s when Egypt and Syria merged into the United Arab Republic a union that lasted three years. After Hafez Assad rose to power in the early 1970s, Mustafa Tlass became defense minister and the Syrian president's most trusted lieutenant.
When Hafez died of a heart attack in 2000, Tlass helped engineer Bashar's succession to the presidency and guided the inexperienced young doctor. Tlass was the leader of a coterie of old regime figures that critics blamed for reining in moves to liberalize the Syrian regime.