ISIS has lost more than a quarter of the territory it once controlled and the area under its hold in Iraq and Syria is roughly the size of Sri Lanka, according to new data.
Security and defence analysts IHS say the terror group's control has reduced by 28 per cent since its height in January 2015.
In 2015, the ISIS's territory shrunk from 90,800 square km to 78,000 square km, a net loss of 14 per cent. In the first nine months of this year, ISIS' territory fell from 78,000 square km to 65,500 square km - IHS analysts said.
As of October this year, the ISIS controls roughly 65,500 square km in Iraq and Syria, which is roughly the size of Sri Lanka, they said.
IHS Conflict Monitor released its last territory report in July 2016. As of July 4, 2016, the ISIS-controlled roughly 68,300 square km in Iraq and Syria, about the size of Ireland.
"The Islamic State's territorial losses since July are relatively modest in scale, but unprecedented in their strategic significance," said Columb Strack, senior analyst and head of the IHS Conflict Monitor.
"The loss of direct road access to cross-border smuggling routes into Turkey severely restricts the group's ability to recruit new fighters from abroad, while the Iraqi government is poised to launch its offensive on Mosul," he said.
The ISIS's losses in Syria over the last three months have been concentrated in northern Aleppo province, where Turkish proxy groups have pushed the jihadists back to around 10 km from the border.
In Iraq, government forces have secured Qayyarah Airbase in Iraq's Nineveh province, a critical staging area for the anticipated offensive to liberate Mosul.
However, ISIS losses have slowed in the three months to October. The terror group has lost just 2,800 square km since July.
The slowdown appears to coincide with Russia reducing the number of air strikes against ISIS targets, IHS has observed. At the start of the year, some 26 per cent targeted ISIS, but by the summer it had dropped to just 17 per cent.
"Last September, President (Vladimir) Putin said it was Russia's mission to fight international terrorism and specifically the Islamic State," said Alex Kokcharov, principal Russia analyst at IHS Country Risk.
"Our data suggests that is not the case. Russia's priority is to provide military support to the Assad government and, most likely, transform the Syrian civil war from a multi-party conflict into a binary one between the Syrian government and jihadist groups like the Islamic State; thereby undermining the case for providing international support to the opposition," he said.
PTI
