International observers are now more worried than they’ve even been that the Damascus government could use its nerve agent stockpile to slaughter its own people.

The U.S. doesn’t know why the Syrian military made the move, which began in the middle of last week and is taking place in central Syria. Nor are they sure why the Assad government is transferring some weapons to different locations within the country, as the New York Times reported on Monday.

All that’s certain is that the arms have now been prepped to be used, should Assad order it.

“Physically, they’ve gotten to the point where the can load it up on a plane and drop it,” the official adds.

Sarin gas has two main chemical components — isopropanol, popularly known as rubbing alcohol, and methylphosphonyl difluoride. The Assad government has more than 500 metric tons of these precursors, which it ordinarily stores separately, in so-called “binary” form, in order to prevent an accidental release of nerve gas.