Robert Ford, the US ambassador to Damascus who has been a prominent and vocal critic of the Syrian regime’s harsh crackdown on opposition demonstrators, has been recalled to Washington after receiving “credible threats” to his safety, the State Department announced Monday.

His surprise recall comes as international attention is intensifying on Syria, which has emerged as the focal point of the Arab Spring revolutions following the death of Libyan leader Col. Muammar Qaddafi and the end of the NATO mission to support Libyan rebels.

Mark Toner, a spokesman at the State Department, said that Mr. Ford had been withdrawn from Damascus after “credible threats against his personal safety.” Diplomatic sources say that the threats appeared to have been incitement against Ford in the Syrian press, most of which is tightly controlled by the state.

Mr. Toner said that it was not possible to determine when Ford might return to Damascus, saying it depended on an “assessment of Syrian regime-led incitement and the security situation on the ground.”

Ford, who returned to Washington over the weekend, has proved a constant irritant to the Assad regime for his outspoken views on the seven-month uprising and his contacts with members of the Syrian opposition.

Last month, he was pelted with tomatoes and stones by pro-regime supporters after emerging from a meeting with a leading Syrian opposition figure in Damascus. In July, he infuriated the Syrian authorities when he and the French ambassador visited the city of Hama, then under siege by Syrian security forces.

He struck back at his critics by posting notes on the US Embassy’s Facebook page. In a posting in September, he rejected accusations by the Syrian authorities that the US was inciting “terrorism” in Syria and arming the opposition. Instead, he blamed the Assad regime for perpetrating the worst of the violence.

“And given the extent of the government’s brutality, neither the Syrian protest movement nor the international community will believe that this Syrian leadership desires or is capable of the deep genuine and credible reforms that the Syrian people demand,” Ford wrote.

Ford took up his new posting without formal Senate approval in January, two months before the uprising began. He was the first American ambassador in Damascus since February 2005 when his predecessor was recalled in the wake of the assassination of a former Lebanese prime minister, an act that was widely blamed on Syria.

US President Obama finessed objections by Republican senators to appointing a new ambassador to Damascus by dispatching Ford to Syria during a Senate holiday. However, since then, Ford’s dogged campaigning for the Syrian opposition has won him many admirers in Washington. Earlier this month, the Senate unanimously approved his nomination.

A US official in Washington said that Ford was doing a “great job” and that he would not have been recalled if the threats to his security were not credible.

“We’re all hoping it’s temporary,” the official said. “He’s been tremendously effective out there.”

Over the weekend, US Sen. John McCain (R) of Arizona, hinted that the time may be drawing closer to consider what “practical military operations” could be arranged to help protect Syrian lives. Some 3,000 people have died in the uprising, according to the United Nations.

“The Assad regime should not consider that it can get away with mass murder,” he said at the World Economic Forum in Jordan. “Qaddafi made that mistake and it cost him everything.”

There is little international appetite at this stage for a military intervention in Syria similar to the Libya mission. But that could change given the rising death toll in Syria and signs that the opposition protests are evolving into an armed rebellion.

“World leaders and Syrian opposition leaders should face the fact that the Syrian situation now requires international intervention and that the Assads need to be stopped by any means necessary,” Ammar Abdulhamid, a prominent Syrian opposition activist based in the US, wrote in his daily newsletter Monday.