US-led coalition air strikes in Syria are now responsible for more civilian deaths than ones caused by Russia since 2015, according to Airwars.org, a nonprofit organisation.
Russia began its aerial campaign in support of the Assad regime in September 2015, four years after civil war broke out.
Tracking more than 2,000 reported deaths as result of Russian or coalition air strikes, the organisation said January's civilian toll from coalition air strikes was the highest since Russian involvement in Syrian war.
According to Airwars' data, 223 of the 269 civilian deaths in June this year were caused by the coalition, as compared with figures from the same month last year where 41 of 177 deaths were caused by the coalition.
The organisation's data suggests that the change in the civilian death toll trends is most likely connected to the ceasefire deal brokered by Turkey and Russia in December 2016.
An escalation in coalition air strikes followed the deal, while Moscow's aerial campaign has slowed.
The group also says the US-led coalition campaign against Daesh in Syria and Iraq caused 2,200 additional civilian deaths after US President Donald Trump took office.
After an investigation for The Daily Beast, Airwars said an estimated 2,300 civilians likely died from coalition air strikes under former US President Barack Obama's term.