Daesh militants in Iraq are steadily losing ground. Iraqi forces successfully recaptured the eastern side of Mosul from the militants, forcing the group from Mosul University and advancing to the east bank of the Tigris River which divides the city in two.
All of Mosul's bridges across the Tigris have been destroyed either by Daesh or coalition airstrikes to prevent the movement of the other side. Meanwhile, the city’s western periphery is guarded by Shia Hashd al-Shaabi paramilitaries, who are preventing the militants from easily evacuating to Syria.
Aside from Mosul the militants only retain pockets of territory in Anbar province, where the Iraqis are on the offensive against them in the city of Hawija west of Kirkuk. Daesh has been unable to counter its incremental losses with new offensives. One attempt to stir-up chaos in Kirkuk and takeover the oil-rich city during the opening phases of the Mosul operation last October ended in abysmal defeat.
Consequently, the militants have sought to lash out and launch fresh attacks in neighbouring Syria, where they have had some success in recent weeks.
That's not to say that the group is not under pressure in Syria. Last November the Arab-Kurdish Syrian Democratic Forces (SDF) militia launched an offensive aimed at eventually retaking the group’s primary Syrian stronghold, the northeastern Syrian city of Raqqa.
SDF forces are currently advancing from the north to Raqqa's west, where they are hoping to take the strategically-important city of al-Tabqa on the Euphrates River. Syrian regime forces faced an embarrassing defeat when they attempted to seize al-Tabqa from the militants last June, after being repelled by hundreds of IS reinforcement
Today the SDF claim to have killed at least 620 of the militants since beginning their offensive in early November. Faced with the prospect of losing all of Mosul, from where their leader Abu Bakr al-Baghdadi declared the formation of the so called “caliphate” in June 2014, and possibly losing Raqqa as well, the militants have sought to attack elsewhere.
In mid-December they successfully recaptured the ancient city of Palmyra – which they had previously overrun in May 2015, only to lose it in March 2016 to a Russian-backed Syrian regime advance. This time they are clearly compensating for their previous defeat by destroying parts of the city's Roman-era amphitheater. which.
Presently, in the eastern Syrian province of Deir az-Zour, IS is besieging Syrian regime forces in the provincial capital, attempting to capture the city's military airport, a key Syrian military enclave there. For over two years now Syrian soldiers have fought a Daesh siege on that city, preventing the city from falling to the group.
The group’s offensive in Deir az-Zour this month is the deadliest and most significant in over a year. It has resulted in World Food Programme (WFP) aid air drops to the city's approximate 100,000 civilians halt for two weeks. Russia has responded by sending its large supersonic Tu-22 bombers all the way from Russia itself to bomb the militants in an attempt to halt this offensive.
If the militants manage to defeat the isolated Syrian Army enclave in Deir az-Zour and seize the city, they could set up an alternative headquarters to Raqqa there. Deir az-Zour is approximately 90 miles southeast of Raqqa and deeper into Syrian territory.
Its capture would give Daesh a little more strategic depth against the SDF, their most significant adversary on the ground in Syria, and also an opportunity to re-mobilize and re-organize if they were to lose Raqqa. An opportunity they have been successfully denied in Mosul.
The militant group could even potentially use Deir az-Zour as a launchpad for future incursions into Anbar, Iraq's aforementioned sparsely populated western Sunni Arab-majority province whose major cities, including its provincial capital Ramadi, have been reduced to rubble from the offensives to rout them out.
Daesh has a long strategy of compensating for past losses of territory annexed into their caliphate by either launching fresh offensives or carrying out headline grabbing terror atrocities. For example, after they lost the Iraqi city of Tikrit in April 2015 they were successfully able to compensate for that by overrunning the provincial capital of Anbar and the aforementioned Syrian city of Palmyra in May 2015.
When they lost the Yezidi city of Sinjar to a Kurdish Peshmerga offensive in November 2015 they launched the infamous Paris attacks in the same month.
Today if Daesh loses Mosul, along with Raqqa soon thereafter, capturing Deir az-Zour could give them a chance to cling onto some territory, forestall the inevitable loss of conquered territories that make up their self-styled caliphate and continue to plot and organize attacks against their many enemies across the world.