(Time) “It maybe good for the U.S. administration to understand that the world does not stop turning and does not hold its breath while they do nothing,”

President Barack Obama had a message for the thousands of minority Yazidis under siege by militants in Iraq late Thursday night: “America is coming to help.” But despite humanitarian airdrops Thursday and American airstrikes against the militants that started Friday, many analysts remain skeptical that the U.S. can do much to help in a fluid, fast-moving and increasingly dangerous crisis.

“Things are happening very fast,” Donatella Rovera, Amnesty International’s senior crisis response adviser, told TIME by phone from northern Iraq on Friday. “Obama’s speech [Thursday] sounded to me as though he was reacting to events that happened last Sunday. The situation can change and does change very quickly in these fluid circumstances.”

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