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.

Sakat’s most compelling information was his account of being ordered to use the toxic chemical phosgene in the Daraa area of southern Syria, a stronghold of rebel support, last year. The Syrian defector said that at the time he supervised chemical weapons for the Syrian army’s Fifth Division, based in Daraa. He had been considered as a chemical weapons supervisor for the Damascus area, but that job was given to another officer.

Sakat was summoned last October by his commander, whom he named as Maj. Gen. Ali Hassan Ammar, and told to use phosgene to attack a region north of Daraa that included the villages of al-Sheikh, Maskin, al-Hrak and Buser al-Harir.

Sakat said that according to standard procedures, any such order for using toxic gas would have originated with top military and intelligence commanders, who make up what he called the “crisis management cell.” The chain of command passes through Gen. Jamil Hassan, the chief of air force intelligence, whose bases Sakat said are often used to store the chemical stocks. The chain then passes to a group known as Unit 450, which coordinates logistics for chemical weapons, and to individual geographic commands, such as Unit 416 for Aleppo and Unit 417 for Damascus.

When handling the weapons, Sakat said he was instructed to use a simple word-substitution code, known as the “Khaled 4” template. An order to transport, say, sarin gas to a particular place would be conveyed with a phrase such as “Go bring the milk to Mohammed.”

Sakat, a Sunni Muslim, said he didn’t want to carry out the order to use phosgene against Sunni rebel civilians. So he said he dug a pit and buried the odorless toxic gas and dispersed a non-toxic substitute that was mostly a bleach-like compound. His commanders thought he had performed the mission as ordered.

After the feigned October attack, Sakat said he was summoned by his commander, Ammar, who proclaimed to a group of senior officers: “This is our hero who launched the chemical attack.” Sakat named a half-dozen Syrian officers who were present to hear this accolade.

It’s impossible to verify another claim made by Sakat that during the past two weeks the regime has sent chemical weapons east toward Iraq and west toward Lebanon. Sakat said planning for these movements began just before Russian Foreign Minister Sergei Lavrov’s Sept. 9 proposal for international control of Syrian chemical weapons, when Hafez Makhlouf, the Syrian chief of intelligence, met with representatives of Iranian and Iraqi intelligence in the Yafour district of Damascus.

Soon after the meeting, Sakat said, rebel intelligence sources spotted a convoy of specialized Mercedes and Volvo trucks moving east from Homs toward a village near Syria’s border with Iraq. The intelligence was provided by Syrian army defectors and an operative known as “Abu Mohammed the Octopus,” who briefly joined us by phone. The interview was arranged through representatives of the Syrian Support Group, a U.S.-based advocacy organization.

Sakat charged that another possible transfer of chemical weapons was made by a convoy of 22 trucks from Mezze military airport, southwest of Damascus, toward Lebanon. Just before reaching the frontier, the trucks veered north to the village of Kfer Yabous and then west along a smuggler’s route said to be used by Hezbollah. There’s reason to be skeptical that this transfer took place, since it could probably be monitored by Israel and would immediately make Hezbollah a target for attack.

Sakat said chemical weapons had also been transferred recently to four other locations inside the country, but he didn’t identify them.

In a separate Skype conversation Sunday, a Syrian source inside the country said that chemical-weapons equipment had been moved recently from the Bahous Center for Scientific Research, in the area known as Berzeh, northeast of Damascus. The source, code-named “Ali,” said he didn’t know the destination.

Read more from David Ignatius’s archive, follow him on Twitter or subscribe to his updates on Facebook.