Dozens of Russian warplanes sit idle on the tarmac at this Russian air base in Syria on the fourth day of a ceasefire brokered by Moscow and Washington, the Associated Press reports.

The apparent lull in action the AP says it witnessed by the on a trip to the base Tuesday, March 1, which was organized by the Russian defense and foreign ministries, contrasts with the hectic operation AP reporters saw here on a previous visit in January.

The ceasefire that began Friday has brought a notable reduction in hostilities for the first time in the five-year war that has killed more than 250,000 people, displaced half of Syria's population and flooded Europe with refugees.

But the truce has remained highly fragile with violations reported in many areas with the opposition and the Syrian government blaming each other.