While fighting appears to have largely stopped, both Russia and the Syrian government are accused of continuing attacks in some areas of the country.
The Saudi Arabian foreign minister Adel al-Jubeir accuses Russia and the Syrian air force of violating a cessation of hostilities in Syria.
"There are breaches of the truce by the Russian air force and the (Syrian) regime, and we are now consulting on this matter with the countries of Syria's support group. And I think that the commitment to the truce will be an important indicator of the seriousness of the Syrian regime."
The agreement, brokered by the United States and Russia, marks the most ambitious international attempt so far to reduce violence in the conflict.
More than 250,000 people have been killed and 11 million left homeless in nearly five years of civil war.
The United Nations describes the deal as the best hope yet for peace.
Under the accord accepted by President Bashar al-Assad's government and many of its enemies, fighting was to stop so aid could reach civilians and peace talks could open.
The self-proclaimed Islamic State, also known as Daesh, and al-Qaeda's branch in Syria, the al-Nusra Front, are not part of the ceasefire, though.
It means the Syrian government, Russia and the coalition supporting other Syrian rebel groups reserve the right to strike those two.
British foreign secretary Philip Hammond says all eyes will be watching Russia's actions over the coming days.
"The Russians have insisted on carving out for themselves a right to continue attacking al-Nusra positions, but, in many areas, al-Nusra units are fighting in close proximity to moderate opposition units. And if the Russians use that carve-out as an excuse to go on bombing the moderate opposition, then we can't expect the ceasefire to work and we can't expect it to hold."
At a joint news conference with the Saudi foreign minister, visiting Danish foreign minister Kristian Jensen says the only solution to the Syrian war is a political one.
"But a political solution can only come with a military threat. Otherwise, Assad will continue his barbaric regime, where he has killed hundreds of thousands of his own people and where he has made over half of his population refugees or internally displaced persons. And, therefore, there needs to be a strong alliance of countries that are willing to put the military pressure that is necessary on the Assad regime and to be able to, at the same time, fight Daesh."
While there have been a number of reports of sporadic violence, the level of fighting is said to be markedly down, giving war-weary civilians some respite.
A Syrian man who wants to be known only as Dr Zahed has told the ABC there is an unnerving calm in the northern city of Aleppo.
"It's got silence inside the city. Strange and scary. You know what they say about the silence before the storm? The most difficult thing is you can't expect where the bomb will be and when."
United Nations Syria envoy Staffan de Mistura says he intends to restart peace talks on March the 7th, provided the halt in fighting largely holds.
Share
