And according to Donald Trump, who moments ago was speaking to reporters, he will make a "major decision" on Syria in the next 24-48 hours, subsequently clarifying that the decision will come "very quickly" probably "by the end of today", adding that nothing is off the table.

"Very concerned, when a thing like that can happen, this is about humanity," the president told reporters during a Cabinet meeting.

"We're talking about humanity. And it can't be allowed to happen. So we'll be looking at that barbaric act and studying what's going on."