A Norwegian general appointed by the United Nations to lead an observer mission in Syria has taken command of the operation and called on all sides in the country's year-long conflict to stop the violence.

Major-General Robert Mood arrived in Damascus on Sunday to lead the advance team of about 15 unarmed U.N. soldiers tasked with monitoring an April 12 truce agreement that has been plagued by continued fighting.

Speaking to reporters at Damascus airport, General Mood appealed for a “cessation of all armed violence” to help the observers prevent the collapse of the U.N.-backed cease-fire and other parts of a peace plan mediated by international envoy Kofi Annan. The Norwegian general said the U.N. monitors “cannot solve all the problems.”

Since the truce took effect, forces loyal to Syrian President Bashar al-Assad have continued attacking opposition hubs across the country, while rebel fighters have carried out ambushes of government security personnel. Each side has accused the other of provoking attacks. U.N. Secretary-General Ban Ki-moon also has accused the Syrian government of using heavy weapons inside civilian areas in defiance of the truce.

In the latest violence on Sunday, the British-based Syrian Observatory for Human Rights said Syrian security forces shot and killed two people in the central city of Homs and one civilian in the neighboring Hama region. Casualty figures could not be independently confirmed.

A spokesman for the U.N. mission in Syria said the observers have set up more permanent bases in opposition hubs targeted by the government's 13-month violent crackdown on dissent. Neeraj Singh said the U.N. bases now include the towns of Homs, Hama, Daraa and Idlib.

Singh also said it is a “matter of utmost urgency” for the United Nations to expand the observer team in Syria to include all of the 300 personnel authorized by the U.N. Security Council. It is unclear when the full contingent will be deployed.

General Mood has years of experience in U.N. peacekeeping operations. He led the U.N. Truce Supervision Organization (UNTSO) that monitors Middle East cease-fires from 2009 to 2011.