And why you should still be worried.
Since the Syrian uprising began in March 2011, concerns over the country's chemical arsenal have largely reflected the fear that terrorists might steal them in the chaotic aftermath of Bashar al Assad's overthrow. Military use against the Free Syrian Army seemed less likely, largely because the use of unconventional weapons would violate international law and norms. If it broke that taboo, the regime would risk losing Russian and Chinese support, legitimizing foreign military intervention, and, ultimately, hastening its own end. As one Syrian official said, "We would not commit suicide."
But this week chemical anxieties shifted. President Barack Obama warned Syria that "[t]he use of chemical weapons is and would be totally unacceptable" -- a comment echoed by Secretary of State Hillary Clinton and Secretary of Defense Leon Panetta, both of whom said that use of the arsenal would cross a "red line" for the United States. Despite these admonitions -- and a barrage of reports that Syria is preparing to deploy its chemical arsenal -- it remains doubtful that Damascus is at the point where the use of chemical weapons against rebels makes tactical or strategic sense.
Chemical weapons have rarely been militarily decisive. In World War I -- which marked the historical debut of choking, blister, and blood agents -- they caused only 4 percent of the war's casualties and only 3 percent of those casualties died. Used episodically in the years since, blistering agents rarely achieved notable results. Italy had little success incorporating them into its attempted conquest of Abyssinia (Ethiopia), and Libya's use of blistering agents against Chadian forces in the 1980s had little impact on battle outcomes. Used in isolation, World War I-era chemical agents were relatively ineffective.
Other chemical agents, however -- most notably nerve agents, which kill by shutting down respiration and other vital functions -- have enabled some tactical successes, while killing tens of thousands civilians. The most notable is example is Iraq's use during its war with Iran, which reportedly suffered 60,000 casualties from chemical weapons. Although difficult to manufacture, nerve agents are immensely lethal and, in some cases, easier to weaponize and deliver. First developed by the Germans, these agents include tabun, soman, and sarin.
So, while blistering agents remain a likely element of the Syrian chemical arsenal, it is the regime's likely possession of nerve agent that provokes far greater concern. Experts note that Syria likely has hundreds of tons of sarin -- a lethal dose is approximately half a milligram. Deliverable by planes and artillery, 100-200 Syrian Scud missiles also reportedly serve as a quickly readied additional delivery platform. There is also suspicion that Syria possesses VX, a far deadlier nerve agent that is 100-400 times more toxic than sarin.
But even these weapons have become obsolete for states. They are rarely strategically decisive, they have been obviated by advanced conventional arms (and, of course, nuclear weapons), and they are stigmatized. That is why all but six states belong to the Chemical Weapons Convention, which bans the production and use of chemical weapons. Syria's weapons, produced beginning in the early 1970s with Egyptian assistance, have been intended to deter Israel's nuclear capability and to offset Syrian conventional inferiority. It's unlikely they could have served either purpose, but designed for use in large-scale, state-to-state warfare, Syria's chemical weapons are particularly unsuited for the urban fights that have characterized the civil war. Close-quarters combat renders chemical weapons not only ineffective but counterproductive; with sarin or VX, a simple wind shift could turn the deadly agent against the Syrian military. Syria's likely blister agent -- so called "mustard gas" -- is highly corrosive, remaining a hazard for forces attempting to occupy the affected area.
That doesn't mean Assad won't use chemical weapons -- in particular, there is the possibility of irrational action if the regime is on the verge of collapse. The more isolated the top leadership becomes, the more likely it is to make unsound decisions based on an altered sense of reality. But the greater threat remains terrorist acquisition of chemical weapons if the military loses control over relevant sites and facilities. The Pentagon estimated earlier this year that it would take more than 75,000 troops to secure Syria's chemical weapons against theft -- and that assumes that U.S. intelligence knows precisely where they all are. After the fall of Baghdad, looters gained access to Iraq's Al-Qaqaa military installation, and close to 200 tons of military grade explosives vanished, even though there were 200,000 coalition forces available and the International Atomic Energy Agency had specifically warned of the explosives' vulnerability.
Some commentators have warned that, as with Iraq, intelligence could be faulty: perhaps Syria has no (or few) WMD. Alas, that is unlikely given Syria's early chemical cooperation with Egypt and its perceived need to deter nuclear-armed Israel. Indeed, following the 2007 destruction of its al-Kibar nuclear facility, Syria may well have doubled down on its reliance on chemical, and possibly, biological weapons to afford the country a perceived deterrent against existential threats. Given all the variables in play, it seems all but certain that in the end an inventory of Syria's chemical stockpile will reveal significant gaps in the current assessments.
Uncertainties regarding this crisis are pervasive, yet at least one outcome is highly probable: terrorist acquisition of chemical weapons if the regime falls. Although militarily ineffective for states, chemical agents still evoke disproportionate fear and anxiety with civilians. Used effectively, they are excellent tools for spreading terror beyond their immediate victims to a far wider audience.
The good news is that few terrorist groups would actually be able to use any materials they acquired. Nerve agents require precision and perennial care. Absent the scientific expertise to maintain and replenish various precursors, many of the agents' purity rates will degrade. Depending on how the particular precursor or agent is stored, its shelf-life could diminish rapidly. The United States, for example, applied certain techniques to its sarin-filled munitions that reportedly retained their purity rate at 90 percent for over three decades. In contrast, Iraqi agents, intended for use in a short period of time, degraded to less than 10 percent, and in some cases 1 percent, in less than two years. Actually delivering the weapons is another hurdle.
Unfortunately, some of the terrorist groups operating in or near Syria do in fact possess the operational capabilities to competently control various quantities of deadly chemical agents. Given Syria's porous border, there are legitimate fears that these agents could find their way to Western Europe, Russia, the United States, or elsewhere. Some could also remain in-country, complicating the transition to a post-Assad government. The ethnic and religious divisions that have plagued Iraq are likely to be replicated with the fall of the Syrian regime. Were chemical agents to fall into the hands of armed factions battling for control of the nation, the implications would be stark and ominous. So, the United States is right to worry about Syria's chemical weapons -- it may just be worried about them for the wrong reason.
Javier Manzano/AFP/Getty Images