A high-level Syrian defector has provided a disturbing new account of Syrian chemical weapons operations — including an allegation that some of these weapons have been moved since Russia proposed an international monitoring scheme to destroy the toxic munitions.

The revelations came in a lengthy telephone interview Sunday with Brig. Gen. Zaher al-Sakat, who was a chemical-weapons specialist for the Syrian army until he defected to the rebels in March. Sakat spoke by Skype from a city in Jordan; he said he believes he is a target for assassination by the regime because of his disclosures.

U.S. officials appear to be skeptical of allegations that chemical weapons have been moved outside Syria, to Iraq or Lebanon, as claimed by Sakat and others. So it’s best to treat those reports with caution. But Israeli officials are said to believe that the Syrian regime has been moving weapons in the country to areas of greater regime control, for reasons of security or, perhaps, concealment.