Chemical weapon storehouses cannot simply be blasted into oblivion, experts have said.
They say that is why the United States is probably targeting something other than Syria's nerve agents.
But now there is concern that bombing other sites could accidentally release dangerous chemical weapons that the US military did not know were there because they have lost track of some of the suspected nerve agents.
Bombing stockpiles of chemical weapons — deliberately or accidentally — would probably kill nearby civilians in an accidental nerve agent release, create a long-lasting environmental catastrophe or both, the experts said.
That is because under ideal conditions — and conditions would not be ideal in Syria — explosives would leave at least 20 per cent to 30 per cent of the poison in lethal form.
Daryl Kimball, executive director of the Arms Control Association, a non-profit organisation that focuses on all types of weaponry, said: "If you drop a conventional munition on a storage facility containing unknown chemical agents — and we don't know exactly what is where in the Syrian arsenal — some of those agents will be neutralised and some will be spread. You are not going to destroy all of them.
“It’s a classic case of the cure being worse than the disease.”
He said some of the suspected storage sites are in or near major Syrian cities such as Damascus, Homs and Hama. Those cities have a combined population of well over two million people.
Asked if there is any way to ensure complete destruction of the nerve agents without going in with soldiers, seizing the chemicals and burning them in a special processing plant, Ralf Trapp, a French chemical weapons consultant and long-time expert in the field, said: "Not really."
Mr Trapp said to incinerate the chemicals properly, temperatures have to get as hot as 1,150 degrees.
Experts also say weather factors — especially wind and heat — even time of day, what chemicals are stored, how much of it is around and how strong the building is are all factors in what kind of inadvertent damage could come from a bombing.
There is one precedent for bombing a chemical weapons storehouse.
Nerve gas
In 1991, during the first Gulf War, the US bombed Bunker 13 in Al Muthanna, Iraq. Officials believed it contained 2,500 artillery rockets filled with sarin, the same nerve gas suspected in Syria. More than two decades later, the site is so contaminated no one goes near it even now.
That bunker is a special problem for inspectors because “an entry into the bunker would expose personnel to explosive, chemical and physical hazards”, said a 2012 report by the Organisation for the Prohibition of Chemical Weapons, which implements the international chemical weapons convention.
Pentagon planners are also worried about accidentally triggering a nerve agent attack by hitting weapons stores that have been moved by the Syrian government to new locations.
Over the past six months, with shifting front lines and sketchy satellite and human intelligence coming out of Syria, the US intelligence community has lost track of who controls some of the government’s chemical weapons supplies.
That is a very real risk, said Susannah Sirkin, international policy director for the Physicians for Human Rights, which has been monitoring weapons of mass destruction for more than two decades.
“You would risk dispersing agents into the environment,” she said. “Given that sarin is not seen or smelled, that’s terror.”
Another issue is that by bombing storage sites that are near contested areas in the civil war, the chemical weapons can fall into other hands, including those of extremist rebels or pro-Assad militia.
“What we’re looking at in Syria is an unprecedented situation,” Mr Kimball said.
AP