The debate over the balance of forces in Syria continues to be heightened by every notable event. The defection of Bashar al-Assad's chief of military police, Major-General Abdul Aziz Jassem al-Shallkal, is no exception. This move, which appears to have been planned for some time, is hailed by many as a major boost for Syria's rebels. The reality, as so often in this conflict of almost two years, may - in a context where western governments and their media tend to place substantial reliance on reports from the rebels, and to dismiss regime statements as pure propaganda - be more complicated.
An independent analysis suggests that two aspects of the case are relevant. The first is that while al-Shallkal held a very significant position, he is a Sunni Muslim rather than from Assad's own Alawi community and thus not within the president's inner core. Moreover, he is not the most senior defector so far, and there seem to be few indications that the core power-base of the regime has yet begun to fracture.
The second aspect is that the contours of the war are indeed changing. The balance of power in the bitter fighting of recent weeks has moved in the direction of the rebel forces; the suffering of ordinary people caught up in the war continues to be appalling; there seems little prospect of respite as the winter drags on; and the United Nations envoy, Lakhdar Brahimi, has scant chance of his latest proposal for an interim government being accepted.
A further factor needs to be included in this mix. There is now considerable concern that in the closing stages of Syria's war, stocks of chemical weapons may not remain secure - and it is even possible that elements within the regime may choose to use them.
Any discussion of Syrian chemical weapons starts immediately with the context of the excessive claims of Iraqi nuclear and chemical prowess in 2002-03, which creates a natural resistance to accepting what western governments may now claim about Syria's capabilities.
Syria's stockpile should also be examined on its own terms. The reported visit of Israel's prime minister Binyamin Netanyahu to Jordan to discuss possible action against the Syrian chemical-weapon facilities, should there be any risk of some of them falling into the hands of radical paramilitaries, sharpens the relevance of the concern. It may therefore be timely to attempt a detached assessment.
It is helpful at the start to put the presumed Syrian arsenal of chemical weapons in context. At the height of the cold war in the mid-1980s, the United States and the Soviet Union were estimated to have (respectively) 30,000 and 50,000 tonnes of chemical weapons. These figures are many times higher than current estimates for Syrian stocks at around 1,000 tonnes, which is more in line with those of France before Paris signed up to the chemical-weapons convention soon after its ratification in 1997. After the US and Russia ratified the convention more than a decade ago, their own stocks began to decline and are now well on the way to being destroyed - although the process is complicated, as it can require very high temperature incineration under carefully controlled conditions.
Israel and Syria, for their part, are not party to the chemical-weapons convention. There is a certain irony about Israel's concern over Syrian chemical-weapon stocks, in that Syria's motive in acquiring them stems largely from the calculation in the late 1960s that it was necessary to counter Israel's nuclear dominance with some kind of deterrent that was easier to acquire. The perceived need was triggered by the loss of the Golan heights in the six-day war of June 1967 and made more urgent by the failure to recover them in the Yom Kippur/Ramadan war of October 1973.
Some efforts may have been made to persuade the Soviet Union to provide chemical weapons, but these seem to have come to nothing. The Syrian programme that started in the early 1980s was indigenous, relying on commercially available equipment. By the end of the decade, Damascus had a domestic production programme manufacturing mustard gas (a blister agent) and sarin (a nerve agent). The delivery systems most likely include aircraft, missiles of varying ranges, and artillery. Although stocks may have been widely scattered to minimise the risk of destruction by Israel, there is some evidence that they are now consolidated into fewer secure sites.
Mustard gas may not be lethal except in high concentrations, but it is persistent and is especially effective and very damaging against eyes, nose, mouth and throat. Sarin is one of the earlier of the organophosphorus nerve agents, a chemical quite closely related to some insecticides. It is lethal in very small doses, entering the body primarily through airways and attacking the central nervous system.
Both weapons would limit the capacity of troops to fight, thus serving a military purpose; though they can be countered by appropriate protective clothing and the use of sealed armoured vehicles. Their potentially most devastating impact, though, is against unprotected civilian populations; the attack by Saddam Hussein's Iraqi regime on the Kurdish town of Halabja on 16 March 1988, which killed over 3,000 people and injured many thousands more, is a stark example.
Their effective use depends very much on "controlled release" that takes into account weather conditions, something hard to ensure under chaotic conditions (such as a regime in the final stages of losing control). This does not mean that the Assad regime would refrain from using them in extremis, but it emphasises that the concerns of other states (among them the US, Israel, and Jordan) relate much more to the security of stocks.
Any kind of action to address this concern is fraught with difficulties. There are three possibilities. The first is airstrikes backed up by post-attack drone reconnaissance, though access to bunkers might be blocked (and the Syrian air-defence system is far superior to that of Libya). The second is to combine the deployment of earth-penetrating warheads to break open bunkers with immediately following thermobaric (fuel-air explosive) devices that would produce sufficient heat to denature the chemical agents.
This might seem feasible, but it would carry a high risk of dispersal and put civilian populations at risk (see “How US Might Try to Avert Disaster in Attack on Syrian Chemical Sites”, NATO Watch news brief, via Global Security Newswire, 17 December 2012).
The third option would be to try to cause some release of chemical agents by a limited attack, making the area immediately around the storage bunker too dangerous to approach. This, though, would cause even greater risk of dispersal. If Assad's forces seem likely to use chemical weapons, attempts could be made to destroy delivery-systems or even prevent orders reaching the troops. That might be possible, but could also make it easier for irregular forces to acquire the weapons.
All these considerations make Barack Obama's administration very cautious about attacking Syria over the chemical-weapons issue - not least all these approaches would require the suppression of Syria's air defences, in itself a major military operation which would leave the United States committed to yet another war in the region.
It is therefore more likely that if any action were to be taken against Syrian chemical weapons, Israel would play the decisive role. The Israelis' concern to protect their security, including a determination to prevent radical Islamist groups acquiring weapons of mass destruction, make their position clearer than the US's - even if Washington would offer covert aid to Israel in any attack on Syria. Moreover, Israel's security commitment is so fundamental that it would almost certainly have a lower threshold of “collateral damage” for Syrian civilians than the United States.
This all too feasible sequence reinforces the crucial importance of efforts to reach a ceasefire. Here, the joint leadership of the United States and Russia could still make a difference, and prevent Syria's descent into an even greater nightmare.