Move calls on members of Security Souncil to mobilize against Islamic State, al-Nusra Front

UNITED NATIONS—The Security Council unanimously passed a counterterrorism resolution on Friday that authorizes the use of military force against the extremist groups Islamic State and al-Nusra Front.

The resolution, introduced by France in the wake of terrorist attacks in Paris a week ago, calls on the international community to mobilize and to organize efforts against the global threat posed by terrorism, to block the flow of foreign fighters and to crack down on terrorist finances.

A resolution introduced by Russia on Wednesday wasn’t discussed by members of the Security Council. Western diplomats said it was too broad in its definition of terrorists and allowed Syria’s government to remain in power. Russia, while endorsing France’s resolution, said the blocking of its own resolution was politically shortsighted and that it would continue to pursue its approval.

French President François Hollande plans a diplomatic offensive this coming week in a bid to unite world powers in a campaign against Islamic State. Mr. Hollande will visit the U.S. on Tuesday and Russia on Thursday.

France’s Ambassador to the U.N., François Delattre, called the resolution historic. “The resolution frames our action under international law and upholds the U.N. charter,” he said, addressing the Security Council. “It provides a guarantee that there will be an effective fight against international terrorism.”

Mr. Delattre told reporters on Friday that this resolution will allow France to amplify its military strikes against Islamic State by at least threefold in coming days, with the arrival of aircraft carrier Charles de Gaulle giving France a wider striking capability.

France’s resolution came as a response to Mr. Hollande’s call before the French parliament on Monday for a “grand and single coalition” with the U.S. and Russia against Islamic State. He said the Security Council must adopt a resolution to fight Islamic extremists.

With the unanimous Security Council vote, the terrorist attacks in Paris appear to have at last mobilized the council in taking a unified stand against terrorism brewing in Syria. The council has been criticized for its inaction over Syria’s five-year conflict, largely due to deep divisions among member states on the fate of Syria’s President Bashar al-Assad.

Security Council member nations remain divided on the key question of the future of the Syrian ruler, but Western diplomats said the U.N. was beginning to act on four fronts regarding Syria: a counterterrorism resolution; a cease-fire plan; deploying U.N. monitors; and an authorization for military action against Islamic State.

Russia presented its proposal on Wednesday and France circulated its proposed resolution on Thursday. The competing resolutions threatened to undermine the movement toward unity on the Security Council, but Friday’s vote quelled concerns.

The Russian proposal is seen by Western nations as seeking to legitimize Mr. Assad’s authority, diplomats said.

The French resolution is more tightly focused on Islamic State, along with the related al-Nusra organization. Islamic State has been blamed—and has claimed responsibility—for the terror attacks in Paris and last month’s crash of a Russian airliner in Egypt. The group also is suspected in a wave of terror attacks in Egypt, Beirut and Baghdad.

In some areas, al-Nusra has fought alongside rebel units which the U.S. and its regional allies have backed. But the group has also gone after CIA-backed brigades, particularly in northern Syria.

While action is under way at the United Nations, diplomats are pursuing talks in Vienna aimed at establishing a cease-fire and starting talks between the Syrian regime and opposition groups.

British Ambassador to the U.N. Matthew Rycroft said the resolution will be used by Prime Minister David Cameron to address Parliament in terms of action against Islamic State group. Mr. Cameron has outlined plans to begin airstrikes by the U.K. in Syria.

Mr. Rycroft said it was up to Russia to redraft its resolution to address the issues that divide the Security Council, such as the role of Mr. Assad.