US President Barack Obama has rejected Russian counterpart Vladimir Putin's claim that Syrian rebels had launched the chemical attack in the suburbs of Damascus on August 21.
Washington still believes forces loyal to Syrian President Bashar al-Assad had perpetrated the poisonous attack, News24 reports.
In an interview on ABC's 'This Week' with George Stephanopolous, Obama defended his policy in the handling of the Syria crisis and dismissed criticism of his approach to the issue.
Many analysts and lawmakers had criticized Obama for his bumpy approach to the crisis, by first threatening a unilateral military strike, then asking the U.S. Congress to authorise it, and later asking Congress to postpone the vote to give diplomacy a chance.
Obama said his policy had led to a situation where Syria has acknowledged it has chemical weapons and Russia is now pressuring its key ally to surrender that stockpile.
Obama also welcomed Putin's diplomatic role in the crisis.