The United States is closely watching the situation in the Middle East after rebels overthrew Syrian dictator President Bashar Assad over the weekend.He's said to be in Russia after the country granted him political asylum.President Joe Biden has called the collapse a "fundamental act of justice" after decades of repression, but also "a moment of risk and uncertainty."The Biden administration says senior U.S. officials are now spread out across the region during this transition period as the U.S. works to prevent ISIS from reemerging. Rebels, who overthrew the dictator, are now taking control in Damascus."It's imperative that all actors involved protect civilians, respect human rights especially vulnerable minorities," said Secretary of State Antony Blinken.But while the U.S. sees this as a moment of opportunity, "it's also a moment of risk and uncertainty," Biden added.Biden warned ISIS could try to take advantage of that uncertainty."We will not let that happen," he said.The U.S. remains concerned about their presence in the country."There are tens of thousands of ISIS supporters that are still detained in the Northeast," said Amy Austin Holmes, a research professor of international affairs at George Washington University.Sunday, U.S. forces hit more than 75 ISIS camps and operations in Syria in response."They do believe preliminarily that they were very, very successful in hitting legitimate ISIS targets and further degrading their capabilities," said John Kirby, White House National Security Council spokesperson.This transition is felt on the ground.Syria's prime minister says most cabinet members are still at work, but some state workers are not returning to their jobs.A United Nations official said Syria's public sector has come to an abrupt halt.This as Syrian refugees celebrate after the collapse of Assad's reign.Some say he'll be remembered as one of the most brutal dictators in history."He's used chemical weapons against his own people. He's barrel bombed his own people," Austin Holmes said.The State Department says it's also working to get information about missing American journalist Austin Tice and bring him home. He disappeared at a checkpoint in Syria 12 years ago. President Biden said he believes Tice is still alive, but acknowledges there's no direct evidence.