The vote was 10-0 with five abstentions — Russia, China, South Africa, Indonesia and Qatar. Nine votes were needed for passage.
Current Lebanese Prime Minister Fuad Saniora asked the council earlier this month to establish the tribunal. He cited the refusal of opposition-aligned Parliament Speaker Nabih Berri to convene a session to ratify the statutes to create the tribunal, which have already been approved by his government and the United Nations.
The resolution gives the Lebanese parliament a last chance to establish the tribunal itself.
If it doesn't act by June 10, the U.N.-Lebanon agreement will automatically "enter into force," creating a tribunal outside Lebanon with a majority of international judges and an international prosecutor.
"The divided vote in the Security Council reflected the fear by several nations that an international tribunal may provoke more conflict and pitted Lebanon's prime minister, Fuad Saniora, who favored it, against its president, Emile Lahoud, who opposed it, and divided factions within Lebanon," says CBS News foreign affairs analyst Pamela Falk. "But it was clear that the domestic courts as well as the U.N.-mandated investigation were not getting full cooperation and were not bringing those responsible for the assassination to justice."
The tribunal will be established under Chapter 7 of the U.N. Charter, which deals with threats to international peace and can be militarily enforced.
The Russians, Chinese, South Africans, Indonesians and Qataris all objected to putting the resolution under Chapter 7, saying it is unnecessary because all Security Council resolutions are legally binding. The U.S., Britain and France, which drafted the resolution, disagreed and insisted Chapter 7 must be included.
The suicide truck bombing that killed Hariri and 22 others in Beirut in February 2005 sparked huge demonstrations against Syria, which was widely seen as culpable. Syria denied involvement but was forced to withdraw its troops from Lebanon, ending a 29-year presence.
The issue of an international tribunal has since fueled a deep political conflict between Saniora's Western-backed government and the Syrian-backed, Hezbollah-led opposition. The conflict has taken on an increasingly sectarian tone and erupted into street battles, killing 11 people in recent months.
Chinese U.N. Ambassador Wang Guangya warned that only a tribunal supported by all Lebanese factions can be effective.
The council's move "will give rise to a series of political and legal problems, likely to add to the uncertainties embedded in the already turbulent political and security and situation in Lebanon," Wang said. It "will create a precedent of the Security Council interfering in the domestic affairs and legislative independence of the sovereign state," he added.
Russian U.N. Ambassador Vitaly Churkin said Moscow supports bringing the perpetrators of Hariri's killing to justice, but he said that "given the deep rift in Lebanese society ... that should not lead to negative consequences."
What the council has done, he said, "essentially is an encroachment upon the sovereignty of Lebanon."
But supporters of the resolution strongly disagreed.
"The proposed tribunal is vital for Lebanon, for justice and for the region," British U.N. Ambassador Emyr Jones Parry said.
"This is not a capricious intervention, interference in the domestic political affairs of a sovereign state. It is a considered response by the council, properly taken, to a request from the government of Lebanon," he said.
U.S. Ambassador Zalmay Khalilzad said that "by adopting this resolution, the council has demonstrated its commitment to the principle that there should be no impunity for political assassination, in Lebanon or elsewhere."
"We know it was necessary and right for the council to act now," he said. "The tribunal will also serve to deter future political assassinations. Those who may be tempted to commit similar crimes will know there will be consequences for perpetuating political violence and intimidation in Lebanon."