Nearly a year later, the revolution’s character has changed. There are still protests, boycotts, strikes and funeral marches. But the opposition’s main strategy for overthrowing Bashar al-Assad’s regime has become one of outmuscling it. To achieve that, it is calling for military help from abroad — a request that will be pressed when Friends of Syria, a contact group of mainly Arab and Western countries, meets in Tunis this week.

The switch in strategy is understandable, though regrettable. The endless killing and torture have taken their toll. Homs, Hama and several other cities are being bombarded by Mr. Assad’s forces in what look like medieval sieges and could have similar grisly outcomes. The people worry they will be massacred if they do not take up arms to defend themselves. Meanwhile, they have seen how foreign military intervention in Libya tipped the balance there and got rid of Col. Muammar el-Qaddafi.

The Assad regime probably likes the fact that the opposition has embraced armed struggle. This solidifies its support among its core constituency — the Alawites, who represent about 10 percent of the population — as well as other minorities like Christians. The regime can argue it has to hit back hard, otherwise it will be massacred.

What is more, it has seen brutality work in the past. Mr. Assad’s father survived a rebellion in Hama 30 years ago after killing around 20,000 people.

Nonviolent struggle has about twice the chance of bringing down dictators as armed struggle, according to a study of 20th- and early 21st-century conflicts, “Why Civil Resistance Works,” by Erica Chenoweth and Maria J. Stephan. Among the many reasons, those close to the regime feel less threatened by nonviolent tactics and so are more likely to shift their allegiance, while it is easier to involve millions of people in Gandhi-style civil disobedience than in military operations.

Outmuscling a dictator, of course, also works sometimes. Ms. Chenoweth and Ms. Stephan found that this was particularly so when foreign powers helped. The snag is that armed struggle results in more carnage than nonviolent struggle and reduces the chances that what follows the dictator will be a peaceful democracy. Involving foreign powers, meanwhile, means the revolution has to dance to those powers’ agendas.

Such a script is playing itself out now in Syria. The conflict has increasingly descended into a sectarian civil war, pitting the majority Sunni population against the Alawites, who are an offshoot of Shiite Islam. A glance at the map shows how this could further destabilize a volatile region. Turkey and the Gulf Arab states are Sunni — and outraged by the atrocities committed against their co-religionists. Iran and, to a lesser extent, Iraq are Shiite and do not want to see their man fall.

The West, meanwhile, is worried about the resulting effects on Israel and Iran as well as having some sympathy for a brave people being butchered. By contrast, Russia does not like the idea of autocrats being toppled, as its regime is shaky too.

This is the context of the upcoming Friends of Syria meeting in Tunis. There are various ideas on the table, all fraught with problems. One, touted by the French, would create humanitarian corridors through which aid could be ferried to the trouble spots. The snag is that a large and sophisticated military force would be needed to blast open and protect such corridors.

Another proposal is to create a safe zone by the Turkish border, where refugees and defecting Syrian soldiers could congregate. This could then be a base from which to launch a counterattack against Mr. Assad, in the same way that Benghazi was used against Colonel Qaddafi.

Again, a foreign army would be needed to secure such a haven. Western powers, which have just disengaged from Iraq, do not seem to have much appetite for that. There is also the complication that Russia and China have made it clear they would veto any resolution in the U.N. Security Council authorizing military intervention.

The rich Gulf Arab countries, led by Qatar and Saudi Arabia, may not have such qualms. But they are not in a position to field an army to match Mr. Assad’s. Their main contribution is likely to be giving the Syrian opposition money to buy arms. If enough sophisticated weapons pour into the country, Mr. Assad might eventually be toppled. But the bloodshed would be horrendous, and Syria could be left with radical Islamist gangs as Afghanistan was after the West decided to arm the mujahideen as a response to Soviet occupation in 1979.

The least bad option would be to revert to a nonviolent struggle and support it from abroad with intensified economic sanctions in the hope that enough of Mr. Assad’s support would crumble that he could be eased out. The Syrian people would still be killed, but casualties might be kept lower if they emphasized tactics like labor strikes and boycotts rather than demonstrations, where they are out in the open and sitting ducks.

Defecting troops would also have to be given something to do other than attack the regime. One idea is to use them to persuade even more troops to defect.

Such an outcome does not look terribly likely. Conflicts that turn violent rarely revert to nonviolence. Probably the best known was the struggle against apartheid in South Africa, but that change in strategy took decades. Still, the other options for Syria and the region look ghastly.