Gates added that Americans don't want their country to go to war.
"American people are frankly sick of war," he said.
Gates is not the first to lament Obama's "red line." Rep. Charlie Rangel (D-NY) in September called the President's comments on Syrian use chemical weapons "embarrassing."
Obama drew the "red line" in August 2012, and some have since speculated whether his comments about chemical weapons use in Syria were planned or not.