By Samuel Burke, CNN
Evidence of chemical weapons use gets harder to find with each passing day in Syria.
The Assad regime is blocking U.N. special investigators from entering the country as the Obama administration continues to seek concrete proof.
“It is publicly known that Syria has the largest active chemical weapons program in the world," President Obama's former chief adviser on all matters relating to weapons of mass destruction, Gary Samore, told CNN's Christiane Amanpour on Wednesday.
The only other country that might have a comparable stockpile might be North Korea, about which we know very little, according to Samore.
"The agents that are said to be in Syria's position are mustard gas, which is a choking agent, and two kinds of nerve gas, sarin and VX," Samore told told Amanpour. "They have a well-developed arsenal for delivering these chemical weapons through aerial bombs, Scud missile warheads, artillery shells and rockets."
It would be a very daunting operation for the U.S. and its allies to secure those stockpiles.
"It would require a very large force to be inserted into many different facilities," Samore said. "And, of course, that force would have to be protected."
This is one of the reasons, he said, why the Obama administration is being very careful about deciding when its red line – Syria using chemical weapons – has been crossed.
"Military options are pretty unattractive to either try to destroy the chemical weapons at storage facilities or to seize them," Samore said. "For that reason, I think it's unlikely that those kinds of military steps will be taken until there's a really clear evidence of large-scale indiscriminate use that removes any doubt about what has happened."
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