Syrians are waking up Thursday to a U.N.-brokered cease-fire, wondering whether a deal to end 13 months of violence and bloodshed will hold.

The cease-fire went into effect at 6 a.m. local time without any reports of fresh violence.

Syria's government had promised to comply with the truce set by U.N.-Arab League peace envoy Kofi Annan. But in a statement Wednesday, Damascus warned its armed forces will remain on standby to retaliate against any attacks by armed terrorist groups against civilians or troops.

In the same statement, Syria said the army had successfully fought off “armed terrorist groups” and has “reasserted the state's rule across the country.”

Kofi Annan brokered a six-part peace plan last month that called for Syria's government to withdraw its forces from major urban areas by April 10 and stop combat operations by Thursday.

The Syrian government agreed to the plan, which also called for opposition forces to stop fighting, and said it began a phased withdrawal Tuesday. But opponents say government shelling continued in many areas and that at least 11 people were killed Wednesday in flashpoint opposition areas, including the central Homs region and Damascus suburbs.

The Obama administration says Damascus needs to match its words with deeds.

At a meeting of the Group of Eight leading industrialized nations in Washington Wednesday, U.S. Secretary of State Hillary Clinton expressed alarm at the ongoing violence in Syria, and concern about the problems facing special envoy Kofi Annan in his efforts to bring about a cease-fire and an end to the violence.

White House spokesman Jay Carney cautioned that President Bashar al-Assad's regime has reneged on promises to stop the violence in the past.

U.S. Ambassador to the United Nations Susan Rice said Syria's promise to halt hostilities by Thursday cannot be construed as complying with Annan's six-point peace plan. She said nothing casts more doubt on the credibility of the commitments than the fact that, in her words, “commitments have been made and made, and broken and broken and broken.”

Secretary Clinton said she will again try to convince Syrian ally Russia that the situation in Syria is “deteriorating” and that the chances of a regional or civil war are increasing. She is due to meet with Russian Foreign Minister Sergei Lavrov later Wednesday in Washington.

The United States and its Western partners have pressed for stronger action against Syria for months but have been hindered by Russian and Chinese opposition to what those two nations call outside interference in Syria.

Russia said Wednesday that since the Syrian government had pledged to halt its offensive on Thursday, it is now the armed opposition's turn to do the same.

Syrian Network for Human Rights chairman Mousab Azzawi told VOA Wednesday that the Syrian government continued efforts to punish dissenters, in spite of its promises to the international community, and that Annan should admit that his peace initiative has failed.

“Everything he has been promised by the regime, the regime just tries to find a loophole in the initiative and tries to empty the initiative.”

U.N. officials say more than 9,000 people have been killed in Syria since the uprising began 13 months ago.

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Reuters feed: (English) U.S. SECRETARY OF STATE HILLARY CLINTON SAYING:

“We are alarmed for the ongoing violence in Syria and we are concerned about the problems facing Special Envoy Kofi Annan as he attempts to bring about a cease-fire and the end to violence.''