Increased military pressure against Islamic State fighters in both Syria and Iraq led to the group losing 22 percent of its territory in the past 15 months, with about half of the loss coming since the beginning of this year.
That is the result of analysis by monitoring group IHS, which said the militants are increasingly isolated and being perceived as in decline.
IHS pointed to the area of northern Syria between the Islamic State de facto capital of Raqqa and the Turkish border, where airstrikes from Russia and a US-led coalition combined with Kurdish and Sunni fighters on the ground pushed out the militants and freed key border crossings.