Brig. Gen. Manaf Tlass, member of Bashar Assad's inner circle, defects

Updated at 11:59 a.m. Eastern

(CBS/AP) The defection of a member of the Syrian president's inner circle has dealt a blow to Bashar Assad just as the United States and its European partners are threatening new sanctions and the opposition is urging military intervention.

The U.S. Defense Department confirmed that Syrian Brig. Gen. Manaf 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.

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.

A pro-government website with close links to Syrian intelligence and security circles syriasteps.com," accused Tlass of overseeing "terror" operations and claimed Syrian intelligence officials were well aware of his communications with external entities. According to the site, Syrian army units stormed the senior commander's home in the upscale Mezzeh neighborhood of Damascus, emptied the home completely and confiscated documents, weapons and cars belonging to the fugitive general.

CBS News' George Baghdadi reports Tlass was a member of Assad's closest group of advisers. The two men had been friends since childhood. He is the highest-ranking military official to abandon Assad since the uprising in Syria began more than 15 months ago.

In Paris at the so-called Friends of Syria conference, U.S. Secretary of State 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.

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About 100 delegations were meeting Friday in Paris at the conference, aimed at bolstering the Syrian resistance and pressing Syria's allies to discuss transition strategies for the embattled country after 16 months of brutal crackdowns and civil war.

The United States and its European partners are threatening new sanctions on Assad's regime if he doesn't act fast on a new peace plan, but the fractured and frustrated Syrian opposition is seeking quick military actions instead.

Hashimi, general secretary of the opposition Syrian National Council, said the international community is still moving too slowly.

Going into Friday's meeting, he said he hopes to see a "tough stand" by diplomats, and a no-fly zone to prevent military forces "flying over defected soldiers and civilians and bombarding them."

But military intervention is not on the immediate horizon. U.S. officials say they are focusing on economic pressure, and the Obama administration says it won't intervene militarily or provide weapons to the Syrian rebels for what it considers to be an already too-militarized conflict.

And Russia, a key Syrian ally, isn't taking part in Friday's conference.

The French hosts, meanwhile, have staked out a firm stance against Assad.

What's happening in Syria "is a threat for international peace and security," French President Francois Hollande said.

"Bashar Assad must leave. A transitional government should be formed. It's in everyone's interest," he said. He urged "real and effective" sanctions and urged all participants to pledge support for democratic opposition and organize effective humanitarian aid.

A U.N. resolution could be introduced next week, according to American officials who previewed Friday's gathering in Paris on condition of anonymity. But with neither Moscow nor Beijing in attendance, much will remain dependent on persuading the two reluctant powers to pressure Assad into action.

The objections of Russia and China also effectively watered down Annan's blueprint for transition at a conference in Geneva last weekend. It grants Assad an effective veto over any interim government candidate he opposes. The opposition would gain the same power.

Activists say more than 14,000 people have been killed since the revolt began.