A former Obama official acknowledged Sunday that the U.S. "always knew" an agreement with Syrian President Bashar Assad did not clear all chemical weapons out of Syria, despite the fact that the administration touted the deal as an unequivocal success at the time.

"We always knew we had not gotten everything, that the Syrians had not been fully forthcoming in their declaration," Tony Blinken, a former deputy secretary of state and former deputy national security adviser under Barack Obama, told the New York Times.

John Kerry, then Obama's secretary of state, and Susan Rice, Obama's national security adviser, had both touted a 2013 agreement with Russia, Syria and the U.S. that was designed to rid the Assad regime of its chemical weapons stockpile. Kerry said in 2014 that they deal had resulted in Syria purging "100 percent" of its chemical agents.

But Assad's chemical weapons attack on civilians earlier this week renewed criticism of the Obama administration-brokered agreement and the former president's refusal to back up his threats of military force against the Syrian government.

Ann-Marie Slaughter, a former Obama State Department official, praised President Trump's strikes against Syria on Twitter, contrasting the move favorably with "years of useless handwringing in the face of hideous atrocities."

Other former Obama administration officials blamed Assad for his failure to disclose the entirety of his chemical weapons arsenal.