"I think it's extremely difficult to do something like this during an active conflict, during a war," Col. Richard Kemp told The Jerusalem Post in a telephone interview published Monday.
"I think it'll take a very large amount of time, with a significant amount of military protection so that the inspectors can be as safe as they can be. That aspect will present huge challenges," he said.
"Which country, first of all, will provide the scientists who will take these risks and the military forces to back them up? It's a very dangerous situation. Secondly, to get verification in this kind of situation, I would say, is impossible. It would be very easy for President [Bashar] Assad to hide or remove out of the country significant quantities of chemical weapons."
Kemp's comments came amid allegations from the Syrian opposition that Assad had already begun moving chemical weapons to Lebanon and Iraq.
"The Syrian regime has transferred some of its chemical weapons arsenal to its ally Hezbollah aboard trucks used to transport vegetables," Kamal Labwani, an opposition leader, told the Saudi newspaper al-Watan Monday.
"We have reliable information the Assad regime is smuggling part of its arsenal of chemicals to Russian battleships stationed on the Syrian coast ... ," Labwani said.
The Lebanese daily al-Mustaqbal reported 200 Syrian trucks were loaded with chemical-warfare-related equipment and sent to Iraq Thursday and Friday.
Brig. Gen. Salim Idris, Free Syrian Army commander, said the Assad regime had begun transferring chemical weapons to Lebanon and Iraq.
An agreement between the United States and Russia on Syrian chemical arms may lead to a token show of disarmament Kemp said.
"I don't think it is realistically feasible," he said.
He warned that the result could harm regional and global security.
Assad's position will be strengthened in the view of the international community, Kemp said.
America's deterrence "appears to be degraded as a result of this and Iran's own position is obviously strengthened by what will be its closer relations with Russia," he said.
"Israel appears to be the only reliable power in the region," Kemp said. "America's power and American deterrence is reduced. Israel remains the one reliable power that the world can count on to intervene if the situation gets too dangerous."