The world’s chemical weapons watchdog has repeatedly found traces of deadly nerve agents in laboratories that Syria insisted were never part of its chemical weapons program, raising new questions about whether Damascus has abided by its commitments to destroy all of its armaments, according to a highly confidential new report.

The discoveries of precursors for chemical warfare agents like soman and VX at several undeclared facilities, including two on the outskirts of Damascus, underscored what a 75-page report by the director-general of the Organisation for the Prohibition of Chemical Weapons (OPCW) describes as a troubling pattern of incomplete and inaccurate Syrian disclosures over the past three years about the scope of the country’s chemical weapons program.

Those gaps have confounded the inspectors’ attempts to verify whether or not Syria has fully abandoned its chemical weapons program, fueling suspicions by the United States and other Western powers that the government may be seeking to retain a limited capacity to use the nerve agents and other lethal toxins against the rebels working to unseat Syrian President Bashar al-Assad.