Editor’s Note: The United States in general, and the Trump administration in particular, is often accused of not matching its deeds to its rhetoric. When the Trump administration decided to use force against the Syrian regime after it conducted a horrific chemical weapons attack, some Americans worried we might be getting bogged down fighting yet another enemy in the Middle East while others worried we were doing too little too late. Erik Gartzke of the University of California San Diego strikes a slightly more optimistic note, arguing that the U.S. strike on Syria can and should serve broader U.S. objectives regarding chemical weapons and weapons of mass destruction in general.

***

America's foreign policy is often characterized by excess. We do too much, aim too high, and then lose interest, leaving muddles (or worse) behind. There are limited things we can do with a limited effort spawned by limited interests, even with enormous military capacity. Last week, President Donald Trump instructed the U.S. military to carry out a limited strike in response to evidence that the Assad regime in Syria had perpetrated a chemical weapons attack against his own people. If indeed the goal of the Trump administration is only to deter future chemical weapons attacks, this could work and may have been (even unintentionally) a “wise” use of military force. If instead the objective is, or becomes, something broader, then the administration risks repeating recent U.S. foreign policy excesses, and eventual failures.

There is a basic problem in Syria that most outsiders seem to want to ignore: Someone is going to win. For the conflict to resolve itself, a victor will need to reassert power. Until this happens, the Hobbesian (stateless) state will continue to grind up human life and deliver misery. Several factions vie for power in the civil war. The situation is so chaotic that instability has spilled over to neighboring countries, led to a massive exodus of refugees, and of course enabled the rise of the Islamic State.

If indeed the goal of the Trump administration is only to deter future chemical weapons attacks, this could work and may have been (even unintentionally) a “wise” use of military force.

A humanitarian objective for the international community should be the rapid resolution of the conflict. But here lies the rub: The most likely winners are all horrible scoundrels guilty of crimes against humanity. Further, outsiders cannot agree on who they think should win. This is almost certainly prolonging the conflict and the associated human suffering. U.S. policy has vacillated between inaction (remember Obama’s "red line"), ineffectiveness (support for the notional Free Syrian Army, or FSA), and the nearly counterproductive (a bombing campaign that, in effect, makes us the Iranian Air Force). Russia, for its part, has steadfastly backed the Assad regime, using our rhetoric and half-hearted initiatives to cloak realpolitik machinations in humanitarian trappings.

The FSA, the Kurdish militias, or other groups we favor are not going to win—at least not outright. Factions that are both politically moderate from the U.S. perspective and militarily effective grow increasingly difficult to find in civil wars, as the brutality of the process grinds away at the will of reasonable people and forces many to flee. Those that remain in Syria—the Islamic State, the Assad regime, and Iranian-supported militias—are not our friends, and they are not disposed to see the wisdom or virtue of protecting human rights. With only enough "boots on the ground" to choose targets and advise allies, we cannot pick winners in this civil war, and coalition air support cannot produce moderation or ensure victory for moderate groups, whoever they are. Generally, the Western bombing campaign favors whatever faction is not being bombed, most typically the proxy Iranian militias. It is far from clear how the United States benefits from helping to extend Iranian influence in the region, just as it is far from clear how we benefit from helping Assad, or from assisting (in effect) the Islamic State, for that matter.

But there is a principle that extends far beyond the boundaries of the current civil war, one that is exceedingly important to U.S. and other Western interests and, unlike picking a winner in Syria, is at least amenable to the efforts we are likely willing to exert. Last week's flight of Tomahawks suggests that the Trump administration may have stumbled upon a fight we can and should win. One “dog” we have in the Syrian conflict is preventing the use of weapons of mass destruction (WMD). Chemical weapons are not nuclear, of course, but with good reason they are often considered together as “unconventional” weapons. Chemical weapons are banned by international convention. They are also the only type of weapon in use in Syria that could directly threaten the United States, if deployed by terrorists or other groups. Every recent U.S. administration has opposed their use. The goal in punishing Assad for their use is thus definable, discreet, moderate in scope but extremely important (to us and others), and amenable to our means.

There is a simple message in the punitive U.S. strike against the Assad regime: “Keep using chemical weapons and we will make sure you lose the civil war.” While we cannot pick a winner in a multi-sided conflict in which we oppose all likely winners to some degree, we can guarantee that one faction will not be the winner, especially if we focus our efforts on an issue that is critical to us and others outside the region. Use of WMD is unacceptable. We have made this clear in our declaratory policy, in sponsoring a major international treaty regime, and in the use of sanctions and military force against other transgressors, like Saddam Hussein. Unlike the other weapons being used in the civil war, chemical weapons pose a special danger to U.S. citizens. They will almost certainly become a favorite choice of future “rogue states” and terrorists, especially if we fail to make clear that their use is subject to special retribution.

This message may prove especially effective in Syria, given the unique characteristics of the conflict. Enforcing the WMD taboo with military force is practical under these circumstances. The last thing the embattled Assad regime wants is to face concerted U.S. airpower. So far, Assad has avoided the brunt of U.S. capabilities because of the divided nature of the factional conflict, and because the United States has not (yet) been clear about whom its chief enemy might be. Making WMD the issue for the United States compels Assad to choose between one weapon in his arsenal and the attention of his most capable adversary. He can either continue to use chemical weapons—a weapon with marginal effects in an already bloody war—or he can avoid the focused enmity of the United States. Each time Assad uses or is suspected of using chemical weapons, the United States can carry out an increasing campaign of denying him access to his other weapons. This progression would end in his being shorn of the very tools he needs most to prevail. So, he will back down. The Trump administration will be able to point to a limited military engagement that will have achieved its limited objective of ensuring that WMD use is not tolerated, a message of tremendous and ongoing importance in world affairs.

Insufficiently clear about its strategic objectives at the outset, the Trump administration may be drawn into the broader Syrian quagmire.

The risk is that success will breed failure, as it so often does in U.S. efforts in the region. The temptation of “mission creep” outlives the labels we apply to it in succeeding administrations. No one can or should be indifferent to pictures showing children as victims of attack, but a broader intervention risks the U.S. becoming a perpetrator of abuses as well as protector of the innocent. Insufficiently clear about its strategic objectives at the outset, the Trump administration may be drawn into the broader Syrian quagmire. Observers are already muddying the message from last week’s attack, in large part because the administration has not been explicit as to what the exact objective was. There is still time to delineate a doctrine that reinforces established U.S. policy: Use of WMD is incompatible with U.S. interests and those of the rest of the world, and will be met with vigorous consequences until a perpetrator either ceases or succumbs.

Unfortunately, it is far from clear that the administration is aware of the potential for its own success. While the president said last week that the United States must “prevent and deter the spread and use of deadly chemical weapons,” he had previously, as a private citizen, criticized the Obama administration for considering intervention, arguing that the United States “should stay the hell out of Syria.” President Trump appears to be acting on instinct, posing the risk that he will fail to maintain a consistent position on the non-use of chemical weapons, either falling back into an extreme form of isolationism or allowing himself to be sucked into a broader, ill-defined, and ultimately futile set of objectives in Syria.

One of the most difficult things for a great power to do, apparently, is to limit its own aspirations. Almost any of the finite things one can accomplish through force are possible given America’s extraordinary military means. Much less is likely, however, due to the lack of a U.S. appetite for yet another major ground conflict in the Middle East. In fact, as we often forget, most of what we desire most has already been achieved. As the greatest great power, we have aided, cajoled, or imposed much in the world that is to our liking. It would be very strange indeed if there were not a few items that escape our interest, if not necessarily our power. At the same time, core U.S. interests, and those of our partners, are imperiled by WMD. It is these weapons that pose the greatest danger to our way of life. We must oppose the use of weapons of mass destruction (chemical, biological, nuclear) wherever they appear. To argue against acting on WMD use is to confuse a vital interest with an understandable anxiety about involvement in the Syrian civil war, a larger conflict in which our objectives are weak or inchoate. We may cheer the Trump administration on this point if they recognize, emphasize, and advertise this distinction, and follow through on their policy of eliminating WMD use. But they will undermine their own goals if they instead become mired in another futile effort at nation building in yet another foreign land.