A nationwide ceasefire in Syria brokered by the United States and Russia came into effect on Monday evening as aid agencies prepared to send food and medical supplies to the besieged city of Aleppo.
The ceasefire is the second attempt this year by Washington, which backs some rebel groups, and Moscow, which backs the Assad government, to halt the five-year civil war. Sources on both sides of the conflict have indicated they will respect it.
The British-based Syrian Observatory for Human Rights, which monitors the war from a network of sources in the country, said major conflict zones were calm after the ceasefire took effect at 7pm local time.
The agreement initially aims to stop fighting between western-backed rebels and forces loyal to the Syrian government, and allow aid to enter areas where it is most desperately needed. In later stages it envisages joint US-Russian attacks on the Islamic State, also known as Isis, and other jihadist groups.
Turkey on Monday said more than 30 aid trucks, under UN supervision, were ready to deliver humanitarian supplies to the city, amid hopes that the truce will hold and secure a rare lull in a war that has killed almost 300,000 people and displaced millions from their homes.
“Today after sunset, whether it is the UN or our Red Crescent, they will send food, toys and clothing to the people, mainly in Aleppo, through the predetermined corridors,” Turkey’s president Recep Tayyip Erdogan told reporters.
Britain’s former foreign secretary David Miliband, now chief executive of the International Rescue Committee, said the deal offered the best chance of a ceasefire since the five-year civil war began.
Speaking on BBC Radio 4's Today programme, he said: "The indications are certainly that there is a better short-term chance of a decent lull in the fighting than has ever happened before. The degree of Russian engagement seems to be of a much greater order than of any of the previous ceasefire attempts."
He said aid agencies had been given assurances at the highest level that they would be able to deliver aid over the next week if all sides complied with the agreement.
The proposed truce was announced on Saturday after marathon talks by the Russian and US foreign ministers.
Under the terms of the agreement, the rebels and the Syrian government are expected to stop attacking one another, though the regime can continue to strike at Isis and other jihadi groups, including al-Qaeda’s former Syrian branch. Theoretically, Russia and the US will then establish a joint centre to combat jihadi groups.
One rebel group, Ahrar al-Sham, an influential Islamist force with links to al-Qaeda, has already rejected the deal, saying it would only serve to strengthen Assad’s regime.
Two other rebel groups have written to the US saying they would co-operate, but voiced reservations. They said excluding the former al-Qaeda affiliate group, Jabhat Fateh al-Sham, from the deal, but not foreign militias backed by Iran, showed double standards. They said the exclusion would be used by Russia and the Assad regime as a pretext to attack other rebel groups.
Air strikes on Aleppo and Idlib have killed at least 74 people since the deal was announced, according to the monitoring group the Syrian Observatory for Human Rights.
Syria's state news agency Sana said the Assad government "approved the agreement" for a truce. Speaking during a tour of the Damascus suburb of Daraya on Monday, Assad said: "The Syrian state is determined to recover every area from the terrorists, and to rebuild."
Lebanese Shia militia Hizbullah, which has intervened militarily on behalf of Assad, also announced its support.
Iran too welcomed the deal, but foreign ministry spokesman Bahram Ghasemi cautioned that its success relied on creating “a comprehensive monitoring mechanism, in particular control of borders in order to stop the dispatch of fresh terrorists” to Syria.
Previous attempts to stop the fighting and deliver humanitarian aid to Syria failed within weeks, with the United States accusing Assad’s forces of attacking opposition groups and civilians.
The UN said on Friday the Syrian government had effectively stopped aid convoys this month and Aleppo was close to running out of fuel, making a successful truce even more urgent.
Guardian service