Spencer Ackerman writes: Blink and you’ll miss it, but President Obama just revised and extended his “red line” for stopping Bashar Assad from using chemical weapons against Syrian civilians.

“We cannot stand by and permit the systematic use of weapons like chemical weapons on civilian populations,” Obama said today, per Reuters’ Jeff Mason. It was Obama’s first comments about what he acknowledged was a potential “game changer” since his White House acknowledged yesterday that U.S. intelligence considers reports of chemical weapons use in Syria credible.

The key word in that statement is systematic. The surprise White House acknowledgement, in a letter to senators yesterday, said that the Syrian regime used chemical weapons, particularly sarin gas “on a small scale.” Danger Room reported that the evidence underlying the U.S. intelligence assessment included blood samples that indicated the effects of sarin. Behind the scenes, as Danger Room has earlier reported, the Obama administration has spotted Assad prepping its chemical stocks for use last year, and attempted to block shipments of precursor chemicals.

The statement gives the president wiggle room — something Obama has wanted to preserve throughout the two-year Syrian civil war. Combined with Obama’s call for to investigate and substantiate the assessment of the chemical use, Obama has now implied it would take a widespread use of the chemicals to prompt the U.S. to involve itself more deeply in the rebel effort to overthrow Assad, which is the stated objective of U.S. Syria policy. Foreign Policy managing editor Blake Hounshell suspected yesterday that it would take a much larger use of chemical weapons by Assad to spur a U.S. military response. But even “systematic” use of chemical weapons begs the question of how much sarin and other deadly gasses Assad can use before Obama feels compelled to stop him. [Continue reading…]