The Security Council voted unanimously Saturday to send up to 30 U.N. blue berets to Syria as the spearhead of a U.N. monitoring mission charged with reinforcing a shaky two-day cease-fire between the Syrian government and armed insurgents.

The vote places the United Nations at the center of one of the most volatile crises of the Arab Spring and offers the outside world independent eyewitness to what has unfolded during a 13-month crackdown on anti-government protesters that left more than 9,000 dead and pitched the country into civil war.

The cease-fire that went into effect Thursday appeared to be fraying. There were reports of renewed tank and artillery fire in several areas of the embattled city of Homs, and at least five people were said to have been killed Saturday in the relatively peaceful city of Aleppo when security forces used live ammunition to suppress demonstrators at the funeral of a man killed the previous day.

The Syrian Revolution General Commission, an opposition group, said 17 people had been killed nationwide in the renewed violence, nine of them in the shelling of Homs.

The action by the council followed a contentious round of negotiations that pitted the United States and its European and Arab allies against Russia. Moscow had opposed efforts to include language requiring Syria to empower the monitors with greater freedom of movement and action, saying their mandate needed to be negotiated with the Syrian government.

To secure Russian support, the United States and other key sponsors of the resolution were forced to strip out provisions that would have required Syria to provide unimpeded access throughout the country. Instead, it merely “calls upon” the Syrian government to guarantee “full, unimpeded, and immediate freedom of movement and access” for the U.N. monitors.

‘Under no illusions’

U.S. and European diplomats welcomed the decision to deploy U.N. monitors in Syria but said that they remained skeptical about Syria’s willingness to end its violent repression of anti-government targets.

“We are under no illusions,’’ said Susan E. Rice, the U.S. ambassador to the United Nations. “Two days of diminished violence after a year of murderous rampage hardly proves that the regime is serious about honoring its commitments. Just today, Syrian forces resumed their brutal shelling of Homs and shot innocent mourners at a funeral in Aleppo.”

Still, the council resolution reinforces special envoy Kofi Annan’s six-point plan, which calls on both sides to cease fighting and enter political talks. The plan also urges Syria to release political prisoners, guarantees freedom of movement for journalists and humanitarian aid workers, and allows peaceful demonstrations.

Syria’s U.N. envoy, Bashar al-Jaafari, told the council that his government will “spare no effort to guarantee the success” of Annan’s peace plan and that it supports the plan for a U.N. monitoring mission as long as it does not violate Syrian sovereignty. But he said Syria is engaged in negotiations with Annan’s team on the mandate of such a mission. He also claimed that Syrian opposition elements have been responsible for 50 violations of the cease-fire, a claim that was challenged by Rice and other council diplomats.

Britain’s U.N. ambassador, Mark Lyall Grant, said that 25 monitors have already been selected to participate in the mission and that the monitors should begin arriving in Damascus within 24 hours.

There are serious risks for the United Nations, which has traditionally been reluctant to send its peacekeepers into a hot war where there is no peace to keep and no durable political settlement in place. In Syria, the government and armed and civilian opposition leaders have not even begun talks.

The council’s action Saturday is the first step in a two-stage process that will lead to the establishment of a full-fledged U.N. monitoring mission staffed with about 250 monitors, most of them recruited from other U.N. missions in the region. The resolution calls on the U.N. secretary general to present the council with a detailed blueprint for the monitoring mission by Wednesday. The council is expected to pass another resolution authorizing the new U.N. mission.

The resolution goes beyond Annan’s peace plan by pressing Syria to return its security forces and heavy weapons to the barracks. The Annan plan only requires Syria to begin its pullbacks of military assets from key cities.

The resolution also calls on Secretary General Ban Ki-moon, an outspoken critic of the Assad regime, to report to the council “any obstructions to the effective operation” of the U.N. team, a provision that is likely to increase pressure on the regime to comply. The council will take “further steps as appropriate” if the Syrian government or the opposition fail to comply.

‘A small step’

Analysts said that the new monitoring mission will probably not fundamentally alter the military balance of power in Syria or end the violence but that it may provide a boost to U.N.-backed efforts to mediate a political settlement.

“I don’t think the small monitor team alone can make a difference on the ground,” said Marc Lynch, a Middle East scholar at George Washington University. “Its significance is more as a small step to build momentum behind Annan’s plan, demonstration of international consensus and test of Assad. The drawn-out negotiations for even such a small step don’t bode well. It’s important to push forward quickly or else the point of such a small step will be lost.”

“The initial deployment of monitors is a political gesture and could be undercut by a rapid return to violence,” said Richard Gowan, a U.N. expert at New York University’s Center on International Cooperation. “Nonetheless, the Western powers in the Security Council were right to insist that the monitors should be guaranteed freedom of movement and unimpeded access to civilians.”

Sly reported from Beirut.