The Assad regime's "days are numbered," US Secretary of State Hillary Clinton said Sunday, CNN reported.
"There is no doubt that the opposition is getting more effective in their defense of themselves and in going on the offense against the Syrian military and the Syrian government's militias," Clinton told reporters at a conference about Afghanistan in Tokyo on Sunday, Voice of America reported.
"So the future, to me, should be abundantly clear to those who support the Assad regime: the days are numbered," Clinton added.
However, Clinton has acknowledged that UN special envoy Kofi Annan's efforts to broker a peace plan in Syria have proven to be unsuccessful, Al Jazeera English reported.
"What Kofi Annan said should be a wake-up call to everyone because he acknowledged that there has not been movement by the Syrian regime in accordance with the six-point plan," Clinton said. "The sooner there can be an end to the violence and a begetting of a political transition process, not only will fewer people die, but there's a chance to save the Syrian state from a catastrophic assault that would be dangerous not only to the country, but the region."
More from GlobalPost: Kofi Annan plan for Syrian unity government 'wins Russian support'
Syria's foreign ministry confirmed that Annan will visit Damascus on Monday, Al Jazeera reported.
"It is confirmed that Mr Annan will visit Damascus, within the framework of his mission, for discussions with the Syrian leadership on the subject of the six-point plan," said ministry spokesman Jihad Makdissi.
In an interview with French newspaper Le Monde, Annan said that “evidently we haven’t succeeded” in finding a political solution to the violence in Syria, Bloomberg reported.
Annan also acknowledged Russia and Iran as notable stakeholders in the region.
"Russia wields influence but I am not sure that the events will be determined by Russia alone... Iran is an actor. It has to be part of the solution. It has influence and we cannot ignore it," Annan told Le Monde, Agence France Presse reported.
However, UN Secretary-General Ban Ki-moon has said that the United Nations can continue to play a crucial role in the violence-ravaged country, according to a report to be presented to the Security Council that was obtained in advance by CNN.
More from GlobalPost: Syrian shelling hits Lebanon, shelling 5
Over 17,000 people have died in Syria since the uprising against Assad began last March, the Britain-based Syrian Observatory for Human Rights told Agence France Presse.
On Sunday, Syrian forces attacked Aleppo and Deir Ezzor provinces, killing 13 people, including 10 civilians, the Syrian Observatory for Human Rights told Al Jazeera. 77 people were killed on Saturday, among them 39 civilians, 25 soldiers and 13 rebels.
The violence from Syria spread into northern Lebanon on Saturday, resulting in the deaths of five and and sparking worries that the violence could spread to Syria's neighboring countries.