More children died in Syria in 2017 than any other time during the seven-year conflict there, U.N. Secretary General Antonio Guterres said Monday as the U.S. threatened unilateral action if the U.N. fails to act.

"I am deeply saddened by the immense loss and cascading suffering of the Syrian people," Guterres told the Security Council during a briefing on the status of a 30-day cease-fire the Council approved late last month. "And I am deeply disappointed by all those who have, year after year, by action or inaction, by design or indifference, allowed this to happen."

The cease-fire the council approved in February has failed to stop some of the worst hostilities in Syria, notably in a Damascus suburb where a regime offensive has resulted in mass devastation and loss of life.

"Particularly in eastern Ghouta, airstrikes, shelling and ground offensives have intensified after the adoption of the resolution and claimed many hundreds of civilian lives -- some even reporting the toll at more than 1,000," Guterres said. "I wish to underscore the urgency of seeing medical evacuations, civilian protection, and full, sustained and unimpeded humanitarian access as soon as possible."

Shelling from eastern Ghouta to Damascus has claimed dozens, possibly close to 100, civilian deaths and injuries, Guterres added.

Nikki Haley, Washington's U.N. envoy, called on the Council to act following the cease-fire's inability to stem the violence.

The U.S. ambassador recalled that President Donald Trump had ordered missile strikes on a Syrian air base in April last year in retaliation for a sarin gas attack blamed on Bashar al-Assad's forces.

"We also warn any nation that is determined to impose its will through chemical attacks and inhuman suffering, most especially the outlaw Syrian regime: the United States remains prepared to act if we must," Haley said. "It is not the path we prefer, but it is a path we have demonstrated we will take, and we are prepared to take again," she said. "When the international community consistently fails to act, there are times when states are compelled to take their own action."

The U.S.-drafted text, seen by AFP, would decide on a 30-day cessation of hostilities throughout Eastern Ghouta and Damascus City to begin immediately upon adoption.

The draft resolution would allow "safe, unimpeded and sustained access" for humanitarian aid convoys and "safe, unconditional, medical evacuations in Eastern Ghouta."

A Syrian opposition representative told the council at a separate meeting that military action was a feasible option to stop the violence and force the Syrian regime to the negotiating table.

Hadi al-Bahra, of the Syrian negotiation commission, said "the threat, and if necessary use of limited military action" was necessary to deter violations of the ceasefire.

Compiled from wires