In an interview in Damascus with Fox News, Assad said "it's not a secret anymore" that his government has chemical weapons he now wants to turn over and see destroyed, but pointed out deadly gases such as sarin are easily made under spartan conditions and blamed the rebels.
"We have evidence that terrorist groups [have] used sarin gas," he said. "The whole story [that the Syrian government used them] doesn't even hold together. ... We didn't use any chemical weapons."
An estimated 1,400 people died in an Aug. 21 chemical weapons attack in the Damascus area.
"This is despicable. It's a crime," Assad said.
Assad told Fox News he is "committed to the full requirements" of the agreement for Syria to turn over all its chemical weapons to any country "ready to take the risk of those materials" for disposal.
Assad sounded pragmatic when asked about the tens of thousands of civilians who have died during the more than 2-year-old civil war.
"This is war. You don't have [a] clean war," he said.
Meanwhile, two former Obama administration defense secretaries, speaking together at a forum in Texas Wednesday, criticized their former boss' handling of the situation in Syria.
Robert Gates, a Republican holdover from the George W. Bush administration, and his replacement, Democrat Leon Panetta, both said the president should have acted differently, though they disagreed on whether to use unilateral military action to intervene after a chemical weapons attack that's suspected of killing 1,400 civilians in the bloody two-year civil war, The New York Times reported.
A U.N. report issued this week states the attack used sarin gas, a nerve agent, and the United States has argued evidence in the report leaves little doubt it was carried out by Assad's forces.
U.N. inspectors plan to return to Syria soon to follow up on other allegations of chemical use, the head of the inspection team said.
Ake Sellstrom, leader of the chemical weapons inspection team that visited Syria earlier, said the inspection could occur as soon as next week, CNN reported Wednesday.
Syrian ally Russia criticized the inspectors' report as "distorted" and defended its ally.
Russian Deputy Foreign Minister Sergei Ryabkov also said the inspectors' report was "one-sided" and based on insufficient evidence, Russia Today reported.
"The point here is not about accusing parties," Ryabkov said. "[The] point is ... that those inspectors of the U.N. should come back to Syria to complete their investigation."
Russian news agency RIA Novosti reported Wednesday Syria gave a Russian diplomat evidence opposition forces were involved in the use of chemical weapons in August. The report didn't indicate the nature of the evidence.
Russian Foreign Minister Sergei Lavrov said his country would veto any U.N. motion OK'ing the use of force if Syria doesn't follow through with disposal of its chemical arsenal.
Lavrov also attacked the U.N. report as unprofessional and unconvincing.
The back-and-forth mirrors the domestic debate over military action by the United States.
Speaking at a forum at Southern Methodist University in Dallas, Gates and Panetta both said they would have encouraged Obama to act differently with the Russians.
Gates was particularly critical of the Russian offer to help disarm Assad's chemical arsenal. Asked by moderator David Gergen whether the United States should trust Russian President Vladimir Putin, Gates answered, "Are you kidding me?"
Despite his skepticism over Russian efforts, Gates said he would not counsel the president to strike Syria with missiles.
"My bottom line is that I believe that to blow a bunch of stuff up over a couple days, to underscore or validate a point or a principle, is not a strategy," Gates said. "If we launch a military attack, in the eyes of a lot of people we become the villain instead of Assad. ... Haven't Iraq, Afghanistan and Libya taught us something about the unintended consequences of military action once it's launched?"
Panetta disagreed, arguing the "red line" Obama drew on the use of chemical weapons must be enforced if the United States is to show the world when the United States threatens military action "we back it up."
"When the president of the United States draws a red line, the credibility of this country is dependent on him backing up his word," Panetta said.
Both men said they would not have asked Congress to approve a military strike, saying the risk is too great lawmakers would rebuff the president and weaken him.
The chemical weapons resolution is based on a framework agreement reached Saturday between Washington and Moscow, giving the Security Council authority to review Syria's compliance with the Chemical Weapons Convention, which Syria agreed to join as the U.S.-Russian framework was finalized.
Under the agreement, the Assad regime is expected to submit a "comprehensive listing" of all its chemical weapons supplies and facilities by the end of this week. All the weapons are to be destroyed by June 30.
The U.S.-Russian framework also says if Syria doesn't comply with its obligations, the Security Council would have a right to impose measures under Chapter VII of the U.N. Charter, which lets the council take military action to "restore international peace and security."
But the United States and its allies understand that statement differently than Russia.
Lavrov and other Russian officials say the statement does not actually say the U.N. resolution would be incorporated under Chapter VII. They say it simply lists Chapter VII as an option available to the council at a future date.
This opens the possibility a further resolution would be needed if Syrian non-compliance becomes an issue, the Times said.