A ceasefire billed as the "last chance" to halt Syria's five-year war collapsed on Monday night as air strikes battered Aleppo and a UN aid convoy was hit near the city.
AFP takes a look at why it failed, what took place during the week, and what could happen next.
Why did the truce collapse?
The deal came into effect on September 12, after marathon talks in Geneva between US Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov.
Syria's military declared the week-long truce over on Monday evening, accusing rebels of more than 300 violations.
"We have not had seven days of calm and of delivery of humanitarian goods," Kerry told reporters in New York after the army's announcement.
Russia said rebel breaches made it "pointless" for Syrian troops to uphold the ceasefire, but that it could resume if "terrorists" stopped their attacks.
The deal faced major obstacles from the start.
While Syria's army had announced it would halt fighting, rebel groups never formally signed on, citing reservations about monitoring mechanisms.
The text of the agreement was not made public, and neither the UN Security Council nor the main opposition umbrella group, the High Negotiations Committee, saw the full deal.
Rebels and regime forces traded accusations over violations all week.
The deal came under growing strain at the weekend after fresh strikes on Aleppo and a US-led air raid in the country's east that killed dozens of Syrian troops.
Russian ambassador Vitaly Churkin called the strike a "bad omen" for the US-Russia agreement.
There was also little progress on aid, a key part of the agreement that could have been used to build much-needed trust among Syria's warring sides.
Hours after Syria's army declared the truce over, a deadly raid hit a joint United Nations, Red Cross, and Red Crescent convoy delivering aid to the town of Orum al-Kubra in Aleppo province.
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