Syrian forces began destroying President Bashar al-Assad's chemical weapon delivery systems Sunday, according to a member of an international team overseeing the process. Speaking to Reuters, the official said a joint team of experts from the United Nations and the Organization for the Prohibition of Chemical Weapons (OPCW) began overseeing the process yesterday, after arriving in the war-torn country on Tuesday. Syrian forces have started "destroying munitions such as missile warheads and aerial bombs and disabling mobile and static mixing and filling units," the official added.

The international mission was launched in response to an August 21st chemical attack that killed hundreds outside Damascus. The Assad regime and opposition groups have blamed each other for the attack, which prompted the US to threaten military intervention. The UN has given Syria until November 1st to destroy its chemical weapon production facilities, as part of a Security Council resolution that was unanimously approved last week. The resolution also gives Syria until mid-2014 to destroy all poison gas and nerve agents.

"we're very pleased with the pace of what has happened."

US Secretary of State John Kerry told reporters Monday that he and his Russian counterpart are pleased with Assad's rapid compliance, though he stressed that the mission is still in a nascent phase.

"Let me be crystal clear," Kerry said, "we're very pleased with the pace of what has happened with respect to chemical weapons."

"I think it is also credit to the Assad regime for complying rapidly as they are supposed to," he added. "We hope that will continue. Now, I am not going to vouch today for what happens months down the road. But it is a good beginning and we should welcome a good beginning."

"One injury or death may bring the project to a halt."

Dan Kaszeta, a London-based security consultant and former officer in the US Chemical Corps, says it's difficult to speculate on how long the mission will take, since the precise scope of Assad's arsenal remains unclear. The regime is believed to have an estimated 1,000 metric tons of nerve agents and toxic gas, including sulfur, mustard gas, and components used to make sarin and VX. US intelligence estimates that these materials are stored at between 30 and 40 locations across Syria, though there are fears that Assad has begun hiding or relocating them in the wake of recent developments.

In an email to The Verge, Kaszeta cited "safety and security" as the clearest and most immediate threat to international inspectors, who arrived amid a civil war that has killed an estimated 120,000 people in more than two years.

"One injury or death among the inspection teams may bring the project to a halt," Kaszeta said.