The United States warned Friday that it was ready to return to the UN Security Council for action on Syria if a peace deal fails, accusing President Bashar al-Assad of undermining the plan, AFP reported.
The United States, which has repeatedly voiced fear that Assad would use an official truce to attack the opposition, said it was ready to consider an end to a UN monitoring mission before its initial 90-day period is over.
"It's failed to meet its objectives because Assad isn't living up to his half of the bargain," State Department spokeswoman Victoria Nuland told reporters.
Secretary of State Hillary Clinton "made clear that if in fact this plan fails definitively, we're going to be back in the UN," she said.
"With regard to the 90 days, that's the scope that the UN has given before it reevaluates the mission. But, frankly, we could very well have to draw our own conclusions well before that," she said.
The United States and its European allies supported the plan negotiated by former UN chief Kofi Annan but have been cautious on whether it would succeed.
The plan -- supported by Russia, Assad's main supporter -- declared a truce between the government and opposition ahead of talks for a political solution.
A suicide bombing in Damascus -- which state media blamed on "terrorists" -- killed 11 people Friday, while human rights activists said that regime forces killed three people including a child as they tried to disperse protests.
Nuland said that the United States still believed that "the bulk of the violations of the ceasefire pledge are coming from the regime side."