PARIS -- Less than a week after agreeing with Russia and China on a roadmap for installing a transitional government to end the growing war in Syria, the United States on Friday slammed both governments for “holding up progress” in removing President Bashar Assad and urged the countries of the world to turn up the pressure.

Even as Secretary of State Hillary Clinton decried Assad’s continued hold on power and Moscow’s refusal to dislodge him, a major crack appeared in his regime when Manaf Tlas, a personal friend of the president and a general in the Republican Guard, defected and flew to Paris.

French Foreign Minister Laurent Fabius called the defection “a hard blow for the regime.”

“His close entourage is beginning to understand that the regime is unsustainable,” Fabius said at the end of a conference he hosted on the Syria crisis, attended by 107 countries and organizations, “more than half the planet.”

Clinton said: “Those who have the closest knowledge of Assad’s actions and crimes are moving away, and we think that’s a very promising development.”

Pentagon spokesman Capt. John Kirby called the defection significant and a crack in Assad’s inner circle. But Kirby added that he hadn’t seen any evidence that the pace of defections has been increasing, and he said the regime did not appear to be on the verge of breaking.

"Clearly, the vast majority of the Syrian military continues to follow (Assad’s) orders,” he said.

According to the final statement of the Paris conference, some 16,000 civilians have died in the 16 months since regime opponents – following the uprisings in Tunisia, Egypt and Libya – took to the streets of Syria demanding an end to the 40-year Assad dynasty. But the figure could be a low estimate.

Tlas’ family has been close to the ruling Assad dynasty for decades, and his father, former defense minister Mustafa Tlas, is said to live in Paris. The Republican Guard provides protection for Assad’s government and is said to be commanded directly by his inner circle.

Turkish officials said Tlas apparently fled Syria via Lebanon. Friday morning, Tlas was headed toward Paris, Fabius announced to the Friends of the People of Syria conference Friday morning. But after the conference ended, he said he did not know Tlas’ final destination.

Previous meetings of the foreign ministers, in Tunisia and Turkey, seemed to be a case of anguished rhetoric to camouflage international inaction. But the Paris meeting came at the end of an intense week of diplomacy that brought the first signs of an end to the split that has paralyzed the United Nations Security Council, where Russia and China have repeatedly vetoed U.S.-sponsored resolutions.

In Geneva last Saturday, Russia and China agreed with the United States, France, Britain and the Arab League that Syria should have a transitional governing body with “full executive authority.”

At Russian insistence, the international “action plan” did not explicitly call for Assad’s ouster. But Clinton said Friday that the accord for the first time put the opposition on the same level as the Assad regime, and the fact that the executive authority has to be “formed by mutual consent . . . obviously means that Assad and the people around him are not going to be part of it.”