Syria on Sunday derided President Barack Obama’s decision to hold off on punitive military strikes, but also took precautions by reportedly moving some troops and military equipment to civilian areas.

The Obama administration countered that its case for military action against the regime of Syrian President Bashar Assad is getting stronger, saying it now has evidence that the toxic gas allegedly used in strikes on rebel-held areas was the nerve agent sarin.

The administration predicted Sunday it will obtain congressional backing for limited strikes. After days of edging closer to military action against Syria, Obama suddenly announced Saturday he would first seek approval from Congress, which gets back from summer break Sept. 9.

Assad, in turn, tried to project confidence in his escalating showdown with the U.S., saying in comments carried by state media Sunday that Syria is “capable of confronting any external aggression.”