Hopes have been raised that violence in Syria could come to an end after the government agreed to partially implement a six-point peace plan by April 10.
The news was delivered to the UN Security Council by Kofi Annan, the UN's former secretary-general and its current Syria envoy.
Mr Annan told the council by video conference that the regime of President Bashar al Assad had pledged to remove its troops and heavy weaponry from towns and cities, paving the way for a total ceasefire with opposition fighters within 48 hours of the withdrawal.
Mr Annan asked the council to consider how a ceasefire monitoring mission would work, but warned that there had been no progress yet in terms of implementing that ceasefire on the ground.
Although the development was broadly welcomed by all Security Council members, some voiced concern that Mr Assad has not previously honoured his commitments to the international community.
Susan Rice, US ambassador to the UN, described America as "sceptical", and said some members of the council were worried "the government of Syria would not use the next days to intensify the violence".
She said: "Let's be realistic... We have seen over the course of the last many months, promises made and promises broken.
"The proof is in the action, not in the words."
Syria's ambassador to the UN, Bashar Ja'afari, said his government was working in "good faith" and at the "highest diplomatic levels" to agree to the rest of Mr Annan's plan, which includes allowing humanitarian and media access, and beginning a political dialogue.
He said: "We are expecting (Mr Annan) and some parties in the Security Council also to get the same kind of commitments from the opposition.
"A plan wouldn't be successful unless everybody is committed."
There would be "no room for 'ifs'" on that point, he added.