The Obama administration on Tuesday harshly criticized President Bashar Assad's latest effort to defend his regime's crackdown on protesters, saying it illustrates how unfit he is to lead a democratic transition in Syria and that he's learned no lessons after 10 months of deadly repression and no political reform.

Assad vowed Tuesday to use an "iron hand" to crush what he called the terrorists and saboteurs behind Syria's uprising, in which thousands of people have been killed. He adamantly refused to step down, as demanded by increasing numbers of Syrians and the United States. For all its opposition, however, the U.S. conceded that no one's efforts so far have been able to force Assad's ouster or halt the violence against Syria's people.

"Assad manages to blame a foreign conspiracy that's so vast with regard to the situation in Syria that it now includes the Arab League, most of the Syrian opposition, the entire international community," State Department spokeswoman Victoria Nuland said. "He throws responsibility on everybody but back on himself. And with regard to his own responsibility for the violence in Syria, he seems to aggressively deny any responsibility or any hand in the role of his own security forces."

Nuland said the Syrian leader's first speech since June was delivered in the same tone as way back in March, when the first demonstrators began demanding greater democracy after four decades of dictatorship by the Assad family.

The 46-year-old ophthalmologist continued to defiantly paint Syria's increasingly organized opposition as the tools of a foreign conspiracy. But Nuland noted that he failed to outline in any way how he'd meet his commitments to the Arab League's to end the violence, pull army tanks and weapons out of Syrian cities, release all political prisoners and allow for a meaningful dialogue to take place.

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"That's what we're looking to see in Syria," she said, "and obviously this was an effort to deflect the attention of his own people from the real problem."

The U.S. has been calling on Assad for months to step down, convinced that he has no interest in reform.

Nuland said international sanctions are hurting the Syrian regime, but conceded that neither America's pressure nor the various diplomatic efforts from Syria's neighbors have improved life for under-siege Syrians trying to remove their leader. Asked how regime change might come about, Nuland insisted Washington was "not dictating how this needs to go forward, but we're simply saying that in terms of our confidence that he can lead his country in a better direction, that's over."

She told reporters that the U.S. would continue to support Arab League efforts to wring concessions from Assad, even though the U.S. considers his leadership illegitimate, if only because they are forcing him to make promises he isn't keeping. That could help U.S. efforts to get more governments to expand their sanctions against the Syrian regime. Asked to describe what 10 months of diplomatic efforts from Syria's neighbors have produced, she said: "Clearly we have not had success. I think that's obvious from the situation on the ground."

Assad's criticism of Arab League monitors coincided with a report by Kuwait's official news agency that "unknown protesters" attacked a group from the Cairo-based bloc who were in the northern city of Latakia. Two Kuwaiti army officers were slightly injured, the report said.

Online footage posted by activists showed what appears to be a white Arab League vehicle swarmed by Assad supporters in Latakia, some of them dancing on top of the car. Another video shows an Arab League vehicle, battered and with deflated tires, struggling to drive as demonstrators surrounded it and shouted Assad's nickname.

Nuland said the attack underscored the violence in the country, but declined to assign blame.

A U.S. official, speaking on condition of anonymity because of the sensitivity of the situation, said Assad supporters appeared to be behind most cases of reported violence toward monitors. The assumption is the Syrian government is orchestrating the incidents, the official said.