We don't talk much about World War I, but we should. The Great War caused 15 million deaths (not counting the Spanish flu epidemic that followed) and not coincidentally created the modern Middle East. In 1915 at the Second Battle of Ypres the German Army introduced something new into the technologies of warfare: chlorine gas. (The French had used teargas earlier in battle, but this was the first use of lethal gas.) By the end of the war approximately 100,000 troops had been killed by gas, and more than a million had been injured; unknown numbers of those injured died later or suffered severely shortened lifespans as a result, not to mention blindness, paralysis, and numerous other debilitating injuries.
The shock of World War I gave rise to international laws of war, especially the Geneva Convention of 1925. Then came World War II, and a new round of international laws in response to a new set of previously unimaginable atrocities. The goal of these international treaties and conventions was always limited. Not to stop war or even to prevent atrocity, but to prevent the very worst evils. Certain particular things -- chemical weapons, mass dislocation, nuclear weapons, genocide -- provoke a special kind of fear. The word for the special kind of fear these things provoke is Horror.
The experience of war as horror gave rise to the idea of red lines: "this we will not tolerate." The promise was that if these crimes were committed, the whole world would retaliate. The regime that committed these acts truly would place itself outside of human civilization, its "hand against every man."
But of course, time and time again the promised retaliation often never came. Even our horror of chemical weapons turned out to be a matter of strategic convenience when Saddam Hussein repeatedly deployed those agents and at a minimum we let him do it.
The entire discussion of Syria is haunted by the ghost of Saddam. If we were wrong to support him when he gassed Kurds and Iranians and Shiites but we were also wrong to invade to remove him from power, then we are paralyzed, trapped between avoiding the repetition of two past mistakes. But perhaps if America bears exceptional responsibility for permitting Saddam's massive violation of this international norm, then America has special responsibility to force that hideous genie back into its bottle. That was the real meaning of the President's declaration of a red line: he was announcing that the days of American support for the Saddam Hussein's of the world are over.
In Syria, the evidence seems to be incontrovertible that approximately 1,400 civilians were murdered by the deliberate release of chemical weapons. Obama's speech was fundamentally about trying to restore some semblance of deterrence. "If we won't enforce accountability in the face of this heinous act, what does it say about our resolve to stand up to others who flout fundamental international rules? To governments who would choose to build nuclear arms? To the terrorist who would spread biological weapons? To armies who carry out genocide?"
But deterrence is a slippery goal. One problem is that a regime of deterrence is a game-able system: the publicly available evidence makes it pretty clear that the Syrian military is responsible in this case, but there could be genuinely ambiguous or misleading cases in the future. How about, say, Lakshar-e-Taiba in Pakistan; if they detonate a biological device in Mumbai, will the US retaliate against Pakistan? In the case of Afghanistan, we said that the fact that the Taliban government had permitted al-Qaeda to operate within its borders made that government responsible for the attacks of 9/11. Will we follow that logic forward, or not? If the answer is "no,'' then the deterrent effect of any action is likely to be small. Worse, an effective deterrent has to impose a sufficient cost to make a regime refrain from taking the risk of deploying banned weapons in the first place. The whole idea of a "proportionate response" contradicts the premise that chemical weapons and genocide occupy a space that is beyond normal calculations of cost and benefit.
So a serious strategy of deterrence presents a highly unattractive prospect: to commit ourselves to the imposition of deliberately disproportionate pain on regimes that either use or fail to prevent the use of banned weapons. Even in the cases of clear responsibility, will we commit to military response every time chemical weapons are used by a government in the future? If not, what exactly is the conduct that we are proposing to "deter"? At a minimum, any strategy of deterrence has to include publicly taking the position that there will be no more turning a blind eye for regimes who happen to be the enemies of our enemies, and no more free passes for those who merely shelter or sponsor the use of chemical or biological or nuclear weapons.
There is an alternative to deterrence. We can draw the "red line" around our borders, meaning those of the U.S. and its close European allies, Israel, Australia and New Zealand, perhaps a few others. We can say, explicitly or not, that if banned weapons are used against one of those populations America will respond with utter ferocity, but unless and until that happens we tacitly agree that the use of those weapons against other targets is acceptable.
Those are two overwhelmingly unattractive options. But Obama has proposed a response that may be worse than either. He seems to be saying that he wants to see the US take actions that will be carefully calculated not to impose significant costs on the Assad regime. From the regime's perspective, it is difficult to see the reason to feel deterred, particularly if there is the possibility of ambiguous responsibility in a future case ("we don't know where Hezbollah obtained those weapons, why don't you invade Southern Lebanon and ask them?"). This kind of response positively invites future calculations of risk and reward, calculations that by definition will in some instances lead a regime to conclude that it is in their interest to make use of chemical or biological weapons.
I have not mentioned the issue of credibility. Critics of Obama who insist that he was wrongheaded to speak of "red lines" insist that the he now risks the loss of American "credibility," a term whose meaning in international affairs increasingly escapes me. But if we are concerned about credibility we should also worry about how countries across Asia and Eastern Europe are viewing the interactions between Putin and Obama; Putin is publicly positioning himself to be the man who was able to order the American President to back off. That speaks volumes about the relative value of alliance with one or another power.
The whole world really is watching. Obama did not create this box, the Assad government did that. Now the box has been opened -- we have to try and close it up again.