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.