After nine months, the Battle of Mosul has finally resulted in victory of Iraqi allied forces, and the titular capital of ISIS territory, Raqqa may fall soon as well. ISIS has suffered massive losses of soldiers, military equipment and facilities. Its cash flow from oil and other ventures is dwindling.
ISIS has lost 60% of its land since January 2015, with its holdings now reduced to a territory the size of Belgium.
"Losing control of the heavily populated Iraqi city of Mosul, and oil rich areas in the Syrian provinces of Raqqa and Homs, has had a particularly significant impact on the group's ability to generate revenue[.]"
In Syria, ISIS has lost most of the territory to the north and western edge of its range that it controlled a year and a half ago. So far, most of the victories in Syria have not gone to Syria, which continues to lack control over much of its territory in an ongoing civil war with multiple factions that has produced a massive refugee crisis, but to rebel factions in its civil war.
Iraq seems to be doing a better job of reclaiming control of its territory, and it is mostly the Iraqi government together with Iraqi Kurds that are doing so. In Iraq, ISIS controls only two isolated blobs of territory along the Euphrates Valley, one near Mosul and one near Kirkuk (these two areas appear to be the current military priority for Iraqi lead forces at this point) and one small stretch of territory along the Tigris River near the Syrian border.
Almost all of ISIS territory in both Syria and Iraq combined is largely cut off from access to the outside world. It has no ports, no aircraft or airports it can use, no border with Turkey, and no access to the main highways across the desert.
The opponents of ISIS (does it have any sovereign friends?), who are mostly part of a U.S. led international coalition of forces, with particularly large Iraqi and Kurdish components, meanwhile, are continuing to attack its limited military and economic resources can to painstakingly slowly regain the territory that ISIS seized in the blink of an eye. Its opponents have complete control of the air space, advanced weapons, seemingly unlimited budgets for their troops, and greater numbers of troops.
It may be largely a slow war of logistics and attrition at this point, but ISIS certainly seems to be losing it.