President Obama, in an address to the nation on Syria, said Tuesday that while he had resisted calls for military action in the country’s civil war, the situation “profoundly changed” after the Assad regime “gassed to death” hundreds of people last month.

The president addressed the nation a little more than a week after declaring he would seek congressional support for a military strike on Syria, in response to a chemical weapons attack on Aug. 21.

But the environment changed rapidly over the past two days, forcing Obama to recalibrate his approach and walk back his “red line” threats, while still leaving open the door to military action. He is now expected to call for a pause in congressional consideration of the use of force.