Thus far, President Obama has been careful to avoid any suggestion of US military intervention in Syria, but now, for whatever reasons, he has chosen to warn of a red line for US action, and that is the deployment and/or use of chemical and biological weapons (although where,  by whom and against whom is not entirely clear). Speaking at a press conference in the White House on 20 August, Mr Obama emphasized that "we cannot have a situation where chemical or biological weapons are falling into the hands of the wrong people," and that "we have been very clear to the Asad regime, but also to other players on the ground, that a red line for us is when we start seeing a whole bunch of chemical weapons moving around or being utilized. That would change my calculus."  He added that "we have put together a range of contingency plans. We have communicated in no uncertain terms with every player in the region that that's a red line for us and that there would be enormous consequences if we start seeing movement on the chemical weapons front or the use of chemical weapons."