I'm relatively sanguine about the signs that Syria may be preparing to deploy chemical weapons:
Syrian forces began combining chemicals that would be used to make deadly sarin gas for use in weapons to attack rebel and civilian populations, a U.S. official tells CNN.This, if true, is certainly a necessary precursor to deploying sarin. It also places a deadline for the use of the sarin: after a few weeks it is likely to have degraded significantly. So what might they be planning to do in the next few weeks?
Why would the Syrian military initiate (or, at least, appear to initiate) their sarin chemical munitions? If they actually intend to use them, what are the targets? Chemical munitions are effective against wide areas; either to deny the attacker the ability to move across them - which seems irrelevant in the context of the guerilla war being conducted by the Syrian rebellion - or to hit a concentration of forces in a town or city. The latter seems more probable, and just the threat of it may force the rebels (and civilians) to flee major towns and cities in order to present a less focused target. The weather in Damascus is currently showing a high of 17C and low of 8C, with potential light rain - assuming similar conditions across Syria, these are good conditions for deploying chemical munitions as the lack of bright sunshine and heat improves the persistence of the chemicals.
The use of chemical weapons against civilians in recent years has been very limited. The most infamous is Iraq's March 1988 attack against the Iraqi Kurdish village of Halabja. This involved a mix of chemical munitions: mustard gas and the nerve agents sarin, tabun and VX, and killed around 5000 civilians more or less immediately. International condemnation afterwards was widespread, though international action against Iraq was notable by its absence. Perhaps this has emboldened Syria, believing that the use (or the threat of use) of chemical munitions is essentially risk-free. Despite Turkey's concerns, I don't see Syria being stupid enough to launch a chemical attack on Turkish territory, causing NATO to invoke Article 5 and giving the USA, UK and Turkey free rein to bomb the bejasus out of Syrian command+control installations; gassing its own citizens, however, may still be viewed as safe.
Perhaps surprisingly, US Secretary of State Hillary Clinton has made the right call:
"I'm not going to telegraph in any specifics what we would do in the event of credible evidence that the Assad regime has resorted to using chemical weapons against their own people. But suffice it to say, we are certainly planning to take action if that eventuality were to occur," Clinton told reporters.Assuming no-one from D.C. leaks the actual plans (and that seems to be a big assumption, but we live in hope) this is near-ideal. It warns the Syrians that the US has publicly committed to action in the event of an attack, but gives them no real idea what scale, duration or focus that action might take. Uncertainties are the last thing that military planners want - especially where the most powerful military on Earth is involved.
The reaction of members of the UN Security Council to a high-casualty use of chemical weapons against civilians would be fascinating. The US and UK would condemn it and try to organise a vote approving use of military force against Syria to retaliate. France - who knows. Russia and China would no doubt veto it and instead propose some mealy-mouthed admonishment. The other members of the Security Council are Azerbaijan, Colombia, Germany, Guatemala, India, Morocco, Pakistan, Portugal, South Africa and Togo; I suspect most of them would sanction military action on the pragmatic grounds of staying on the good side of the USA, while not actually getting involved themselves. But with the Russo-Chinese veto, it's not going to be sanctioned anyway, so approving military action is consequence-free.
Would the USA and UK try a non-UN sanctioned strike against Syrian command+control? I don't see why not. No-one actually likes Syria, and while Russia, China, North Korea, Iran and Venezuela might protest the attack (wary of the precedent of allowing other nations to have a say in the right of a country to slaughter its own civilians) I doubt there will be much political downside for President Obama and PM Cameron. Sending a few B2s over some randomly selected military bunkers to unload 5000lb GBU-28 bunker-busters would make quite the mess. Alternatively, picking a large Syrian armoured formation in the open and dispensing CBU-97 Sensor-Fuzed Weapon containers would make it suddenly extremely immobile and ineffective.
Assuming the Syrian military is smart enough to see through the politics and doesn't actually want to be pounded, my best guess is that they're worried about concentrations of rebel forces and want to provoke rebels and civilians into leaving towns and cities near the front line; this would give them breathing space to mass forces and either counter-attack or reinforce defences. If so, they have about a month to make the best of it before it becomes apparent that the sarin-mixing was all a big bluff...