You know that besides there being a difference between lying and having incomplete information, there's also the fact that they can manufacture more of that stuff right? Or bring it in? As in, that statement could have been true when it was made?
She lied. Here is the quote from WaPo. She asserted that the administration found a solution to the goal of dealing with the threat of chemical weapons. Not chemical weapons, but the threat of those weapons. She asserted that the solution to that threat was found in diplomacy. She lied. That threat was not eliminated. Whatever chemical weapons existed or didn't exist before during or after their applied solution did not remove the threat those weapons represented as she asserted in her comments.
“We were able to find a solution that didn’t necessitate the use of force that actually removed the chemical weapons that were known from Syria, in a way that the use of force would never have accomplished. Our aim in contemplating the use of force following the use of chemical weapons in August of 2013 was not to intervene in the civil war, not to become involved in the combat between Assad and the opposition, but to deal with the threat of chemical weapons by virtue of the diplomacy that we did with Russia and with the Security Council. We were able to get the Syrian government to voluntarily and verifiably give up its chemical weapons stockpile.”
— Susan E. Rice, then-national security adviser, in an interview with NPR’s “Morning Edition,” Jan. 16, 2017