THE CARNAGE in Syria grinds on, with a human toll that mounts every day. By most estimates, nearly 40,000 people, most of them civilians, have been killed, and more than 10 percent of the country’s 23 million people have been displaced, including 400,000 who have fled to Turkey, Jordan, Lebanon and other nearby countries. Fifteen months after President Obama called for the end of the regime of Bashar al-Assad, there is no indication that it will give way to rebel forces, or manage to defeat them, in the foreseeable future. Instead the war is slowly spreading — with firing across Syria’s borders with Israel, Turkey and Lebanon. Radical jihadist groups linked to al-Qaeda are gaining strength.

Nevertheless, there has been one positive development in the political arena: the formation of an opposition front that is more inclusive and more grounded in Syria than previous rebel groups. The National Coalition for Syrian Revolutionary and Opposition Forces, formed in Qatar on Nov. 11, is headed for now by Moaz Khatib, a moderate Muslim cleric who left Syria only in July and who has advocated a pro-democracy, anti-sectarian agenda. The State Department, which worked hard to forge the coalition, deserves credit for helping to create a body that could remedy what has been one of the biggest obstacles to greater international support for the rebels.

The Obama administration is still moving more slowly and cautiously than its allies in backing the new leaders. Unlike France, Turkey and the Persian Gulf states, it has not yet recognized the coalition as the “sole legitimate representative” of the Syrian people. Officials say they first want to see the new leaders show that they can establish themselves inside Syria, gain popular support and win the allegiance of most of the armed groups — which were not included in the Doha accord.

There is some value in giving the opposition such an incentive to perform. At the same time, the new coalition won’t succeed without strong financial and material backing from the outside. In particular, its ability to gain control over the scores of armed rebel formations around the country will depend on its ability to provide them with money and weapons — in particular, arms that can be used against the government’s air power. The gulf states are already providing guns but not always to groups the West would favor. The jihadists, meanwhile, have developed their own supply lines.

These facts have caused the French government to suggest that the European Union lift its arms embargo on Syria so that “defensive weapons” could be given to rebel groups through the new coalition. Mr. Obama appears to be resisting that step; at his news conference on Wednesday he again expressed concern that weapons could fall into “the hands of folks who would do Americans harm.” Yet such extremists are already obtaining arms; the real danger is that the groups favoring a democratic and non-sectarian future for Syria will be the least well-equipped.