For nearly two years, Western governments have been looking for reasons not to send troops to Syria. And despite the most recent claims about the use of chemical weapons in Syria, they're still looking.
According to the US defence secretary Chuck Hagel: "Our intelligence community does assess, with varying degrees of confidence, that the Syrian regime has used chemical weapons on a small scale in Syria, specifically, the chemical agent sarin."
There are two key phrases in that sentence: "varying degrees of confidence", and "on a small scale."
The UK foreign office says it has "limited but persuasive information from various sources" of chemical weapons having been used in Syria. Again, note the caveat: "limited". It doesn't take a genius, does it, to work out that they are treading very, very gently.
This morning, David Cameron said there is "limited but growing" evidence that Syrian government troops have used chemical weapons. It is, he said, "extremely serious, this is a war crime."
Why does the chemical weapons issue matter? Because for many months now, President Obama has said that if the Syrian military use chemical weapons against rebel forces, they will have "crossed a red line". As recently as last month, he said: "We will not tolerate the use of chemical weapons against the Syrian people."
So, what does "we will not tolerate" mean? Last August, Mr Obama said the use of chemical weapons "would change my calculus … That would change my equation.” Last month, he told Syria's president, Bashar al-Assad, that if such weapons were used, “the world is watching, we will hold you accountable.”
But last night, in a letter to US senators, the White House said merely that it will now press "for a comprehensive United Nations investigation that can credibly evaluate the evidence and establish what took place."
The watch-word is caution, not a call to arms.
No one should be surprised if governments treat intelligence assessments these days with a high degree of caution. If the Iraq experience taught them anything, it was that the spooks don't always get it right. "Evidence" of chemical or other so-called weapons of mass destruction is not always quite what it seems.
So let's put all that to one side, take a couple of steps back and ask a basic question. What is the desired goal in Syria? Suppose it's simply an end to the bloodshed, after the deaths of at least 70,000 people over the past two years, more than 6,000 of them last month alone.
Would foreign military intervention end the bloodshed? Well, we have some precedents to guide us. Bosnia, for example, in 1995, or Kosovo in 1999, where foreign military intervention did end the slaughter of civilians. Ditto in Sierra Leone in 2000, and East Timor in 2006.
In Iraq, a reviled dictator, Saddam Hussein, guilty of having used chemical weapons against his own people (the Kurds in Halabja in 1988), was overthrown and executed. Likewise in Libya, where foreign military action enabled local rebel forces to overthrow, and then murder, another reviled dictator, Muammar Gaddafi.
But the Iraq and Libya precedents aren't as clear-cut as some pro-intervention advocates might like. Sure, the tyrants were toppled -- but did the killing stop? On the contrary: in Iraq, certainly, and in Libya to a somewhat lesser extent, the level of the killing was actually higher after the foreign intervention than before.
It's more than a year now since the secretary-general of NATO, Anders Fogh Rasmussen, asked the key question: if international military forces were to intervene in Syria, how likely do you think it is that they would be able to create a sustainable solution to the crisis?
The unfortunate truth, as I pointed out at the time, is that there is always a risk that by stepping in to prevent people dying, you end up being responsible for even more people dying. There is no iron rule of politics that says that what follows a brutal dictator will always be better than what went before.
None of this means I think foreign intervention in Syria is necessarily a bad idea. There may well come a time when the sheer horror of what is happening there is too much for Western (and some Arab) governments to stomach.
For now, though, it looks to me as if the assessment in Washington, London and Paris is that we have not yet reached that moment. Callous though it may sound, the needle on the horror-meter has not yet gone high enough.
There's one other factor for you to consider: it still looks inconceivable that if there is to be foreign military intervention, it will have the backing of the UN security council. So if you were against the intervention in Iraq on the grounds that it wasn't approved by the UN, you need to come up with a good reason why that wouldn't matter in Syria.