American intelligence agencies had indications three days beforehand that the Syrian regime was poised to launch a lethal chemical attack that killed more than a thousand people and has set the stage for a possible U.S. military strike on Syria.

The disclosure — part of a larger U.S. intelligence briefing on Syria’s chemical attacks — raises all sorts of uncomfortable questions for the American government. First and foremost: What, if anything, did it do to notify the Syrian opposition of the pending attack?

In a call with reporters Friday afternoon, senior administration officials did not address whether this information was shared with rebel groups in advance of the attack. A White House spokeswoman declined to comment on whether the information had been shared.

But at least some members of the Syrian opposition are already lashing out at the U.S. government for not acting ahead of time to prevent the worst chemical attack in a quarter-century. “If you knew, why did you take no action?” asked Dlshad Othman, a Syrian activist and secure-communications expert who has recently relocated to the United States.