A senior Obama administration official dismissed the action, saying it was "too late to be credible." Meanwhile, Iran warned that the U.S. would face "severe consequences" if it crossed the red line.

President Obama is meeting with his national security team to discuss reports of Syria's use of chemical weapons, as the U.S. "repositions" warships armed with cruise missiles in the Mediterranean.

Syrian children account for 1 million of the 1.75 million Syrians who have fled their country since the beginning of the upheaval in 2011, the United Nations says.

Opposition forces say chemical weapons deployed by the Assad regime killed scores of people on Wednesday. The regime rejects that charge. The claim has some diplomats warning that it may be time for other nations to step in militarily.