From NBC News:
The military has loaded the precursor chemicals for sarin, a deadly nerve gas, into aerial bombs that could be dropped onto the Syrian people from dozens of fighter-bombers, the officials said.
As recently as Tuesday, officials had said there was as yet no evidence that the process of mixing the "precursor" chemicals had begun. But Wednesday, they said their worst fears had been confirmed: The nerve agents were locked and loaded inside the bombs. […]
U.S. officials stressed that as of now, the sarin bombs hadn't been loaded onto planes and that Assad hadn't issued a final order to use them. But if he does, one of the officials said, "there's little the outside world can do to stop it."
Sarin gas was most famously used by Saddam Hussein against the Kurdish town Halabja in 1988, leaving thousands dead. The nerve agent was also used in a terrorist attack that killed 13 people in Tokyo's subway system in 1995.
Fears that the Assad regime might authorize the use of chemical agents against Syrian rebel forces have grown more acute recently, as the 20-month-old civil war inched closer to the capital city of Damascus. U.S. Secretary Of State Hillary Clinton said on Wednesday that such an attack was possible, warning that "those responsible would be held to account."
According to Fox News, Syria has "60 days to use these bombs until the chemical mixture expires and has to be destroyed."
CORRECTION: In an earlier version of this article, Bashar al-Assad's name was misspelled. We regret the error.
Captions provided by AP.