The UN Security Council on Saturday unanimously voted for a resolution to approve international ceasefire monitors going to Syria.
UN Resolution 2042 approved the first 30 unarmed military monitors, who are expected to to leave within days. A new resolution with a full mandate will be required for the full monitoring mission of more than 200 observers.
Earlier, Syrian troops shelled two neighbourhoods of the flashpoint central city of Homs on Saturday, even as a hard-won UN-backed ceasefire entered its third day, monitors said.
There was no immediate word on any casualties from the hour-long morning bombardment of the city's Jurat al-Shayah and Al-Qarabis neighbourhoods, the Syrian Observatory for Human Rights said.
The Baba Amr district of Homs became a symbol of the protest movement against President Bashar al-Assad's regime launched in March last year when it came under a devastating month-long pounding before being overrun by government forces at the beginning of last month.
The UN Security Council was to vote later on Saturday on a Western-drafted resolution allowing a ceasefire observer mission in Syria even though Russia's support remained in doubt.
The United States called for the vote after a second day of wrangling with Russia over security guarantees for the first 30 unarmed military monitors that UN-Arab League peace envoy Kofi Annan wants in Syria early next week.