Once again, the United States is agonizing over whether to conduct another humanitarian intervention, one with strong strategic considerations—how to get rid of Assad and hopefully end Syria’s civil war.

For the past year, the United States and its friends have tried denunciations, threats and knowingly futile diplomacy. A few countries have taken to covertly supplying some arms to his opposition. Some Americans, notably in Congress, find all that grossly inadequate. They strongly object to a policy they believe is based on the assumption that it’s only a matter of time before Assad falls. There is a small intellectual war over what might generate more robust NATO/Arab/Turkish military action to resolve the unending humanitarian disaster. Some look to past precedent: Srebrenica, with its eight thousand murdered during the Bosnian conflict, finally produced a serious military intervention. But after sixteen months with thirteen thousand dead, one hundred thousand refugees, a half million displaced and all the numbers steadily rising, Syria still waits.

Since its use in Somalia, humanitarian intervention has generated a continuing, ever-fiercer debate in Washington. Indeed, this century the international community came up with a supposed answer to prevent or cope with these man-made disasters: “the responsibility to protect.” This doctrine holds that when a government destroys or allows masses of its people to be destroyed, the international community can and must intervene—not initially militarily, but if nothing else works and a military solution is feasible, then with force. The problem, not surprisingly, is that governments have rarely implemented it.

The sad fact is there is simply no agreed basis for military intervention in terrible situations. It is hard to mobilize the “international community” for military action. The first international resort is (usually ineffective) diplomacy, while providing important humanitarian assistance to the internally displaced and refugees. Frequently, the lack of Security Council agreement is cited as a principal reason for delaying military action, except of course when the United States feels the need to act. The number killed is certainly a factor, but it’s hardly the only one—the impact of recent wars, diplomacy, domestic politics, presidential prestige, costs, strategic considerations, likely international support and sustained public advocacy also play a role. With Syria, there is also the opposition of Russia and China in the Security Council, as well as greater concern for the uncertainties of war and the law of unintended consequences.

A Mixed Record

The Cold War period had its share of humanitarian disasters: China’s Great Leap Forward cost perhaps thirty million lives, the Cultural Revolution affected large but unknown numbers, and a million people were killed in Cambodia after the Khmer Rouge victory in Indochina (for which the United States bore great responsibility). Those incredible disasters never had a chance of prompting foreign intervention, and they have been left largely to the historians (except for the continuing tribunal set up to try senior Khmer Rouge leaders). It is more instructive to briefly examine the history of post–Cold War humanitarian interventions.

Somalia was the first. After much inside badgering, the elder Bush administration, in its last days in 1992, sent military forces to deal with a serious famine and stayed to try to keep the peace while the country broke apart. The Clinton administration fled after a U.S. helicopter was destroyed, and Congress hysterically called for shutting down the whole enterprise. The U.S. failure in Somalia led to unwillingness to respond quickly to prevent massive murders in Rwanda in 1994. The United States recently has returned to a badly failed Somalia with special forces, this time not for humanitarian reasons but to wipe out Al Qaeda. There is no U.S. interest in a more robust military effort there, leaving it to inadequate numbers of African forces doing their best to end the violence.

Bosnia was America’s baptism into humanitarian intervention. But it took three years, over a hundred thousand people were killed and massive ethnic cleansing took place. Initially, the United States, following the lead of the EU, promoted unserious diplomacy. A sustained public campaign for intervention and the killing of some eight thousand Bosnians in Srebrenica helped produce a military response that ultimately led to the Dayton accords. But there was a wonderful irony. Washington made peace with Slobodan Milosevic, the man who essentially caused it all. He suffered no punishment and was given an ethnically cleansed ministate to watch over. We can sup with the devil.

Kosovo, the second military intervention in the Balkans, was perhaps the most remarkable of modern humanitarian operations. While there were massive human-rights violations in Kosovo, only forty or so Kosovars were killed by Serb forces in the incident that eventually led to Western intervention—teaching us that casualty numbers are not all that matter in deciding when to intervene. U.S. diplomacy—which I strongly supported—led to war with Serbia and, once again, peace with Milosevic. This time his country was bombed, but he survived it.

Sudan best represents the distance between incessant Western rhetoric and effective humanitarian intervention. The latter Bush administration negotiated to keep the country together, and the Obama administration later produced an agreement to divide it. But violence never stopped under any agreement. Over the past decade, some three hundred thousand have been killed in Darfur and millions were stored away in refugee camps. Serious violence between North and South continues in disputed Sudanese areas. The Obama administration came to power promising to carry out “robust military measures” to end the violence, but that talk ended once when he took power. Omar al-Bashir, a longtime Sudanese leader indicted by the ICC, has committed far more atrocities than Assad ever did, and Washington talks to his government all the time (though not to him). The United States has not insisted that he leave or done much to try to remove him from power. The Congo is a similar situation, where terrible violence still continues and international forces are not able to change the situation. Both are apparently in the “too hard” category for the international community.

The most recent and much-debated NATO military intervention in Libya took place because there was Arab League support and because the UN Security Council gave its blessing. The half century of despised Qaddafi’s rule made military intervention far more palatable (and easier) than getting rid of Assad. The decision was made with great urgency due to the real possibility of major killings in Benghazi but with little knowledge of opposition forces or preparation for an eventual succession. Libya has been a deterrent to more muscular intervention in Syria because unlike in Libya, Russia nor China made clear they oppose military action to get rid of Assad.

Humanitarianism Resurgent?

We are good at earthquakes, tsunamis and other acts of God. We always stand ready to supply diplomacy, good or bad, and are exceedingly generous with humanitarian assistance, except for North Korea. Our military interventions for humanitarian purposes are now very limited indeed and only occur when success is likely to be quick, casualties light and complications few in establishing political stability.

Syria is strategically important to all interested countries in a way not seen in other interventions. That has prevented a serious response to end the killing. Meanwhile, there are all sorts of internal and external problems already emerging in Syria. It looks as if only sizable additional killings may produce a more militant Western response.

Humanitarian intervention has fallen on hard times, to a great extent due to America’s endless wars and economic decline. Complexity has disillusioned some of its prominent exponents. But you can bet on it returning. America believes it is a uniquely virtuous country, and it has the military means to back that up. Many citizens and the media will be at the forefront promoting serious responses to evil events. The Syrian debacle is hardly the end of the story.

Morton Abramowitz is a senior fellow at The Century Foundation and a member of The National Interest's advisory council.