Weapons across Syria fell silent at 7pm local time (4pm Irish time), after the deadline for a cessation of hostilities in the region passed.
The deal, brokered by US Secretary of State John Kerry and Russian Foreign Minister Sergey Lavrov, calls for a ceasefire between rebel militias and Syrian Government forces and its allies.
Russian officials have said that the ceasefire extends countrywide, but that aerial operations against ‘terrorist targets’ would continue.
If the ceasefire holds for 7 days, US and Russian forces will engage targets identified to be aligned with al-Nusra, an extremist cell associated with al-Qaeda.