The government of Col. Moammar Gadhafi hasn’t destroyed significant stockpiles of mustard gas and other chemical-weapons agents, raising fears in Washington about what could happen to them—and whether they may be used—as Libya slides further into chaos.

Tripoli also maintains control of aging Scud B missiles, U.S. officials said, as well as 1,000 metric tons of uranium yellowcake and vast amounts of conventional weapons that Col. Gadhafi has channeled in the past to militants operating in countries like Sudan and Chad…

Libya was to have destroyed all 23 metric tons of its mustard gas by the end of last year, according to the OPCW, but 9.5 metric tons remain. The Hague-based body said Libya was granted an extension until May to destroy the rest.

Libya also possesses more than half of the 1,300 metric tons of precursor chemicals used for developing chemical agents. The material is believed to be stored in jugs at the former Rabta chemical-weapons facility.