ISIL personnel and weaponry have flooded into southern Syria, and have been heading towards Damascus, as the group redeploys forces that have been fighting for control of Mosul in northern Iraq.
A steady stream of ISIL fighters and weapons, including missiles and artillery, have been trickling from western Iraq and eastern Syria — ISIL strongholds — since December.
But in the face of a sustained military campaign to unseat it from Mosul and north-eastern Syria, ISIL has accelerated the move, according to Syrian rebel commanders monitoring the situation.
"ISIL has concluded there is no hope of winning the battle for Mosul, and so priority has been given to the battle for Syria," said an independent military advisor in Jordan who tracks the group.
As its territory in Iraq shrinks, ISIL has expanded into areas of Syria in which its presence had been lighter. Many of its heavily-armed fighters have attempted to infiltrate into the Ghouta area, to the south and east of Damascus.
It has also set-up a weapons storage facility in Tal Asfer, on the eastern edge of Sweida, a city dominated by members of Syria’s minority Druze community. Sweida remains under the control of forces loyal to President Bashar Al Assad.
And it has reinforced positions in Bir Qassab, a strategically important village to the north-east of Damascus.
Foreign fighters with the group have also bolstered positions it holds in Deir Ezzor, Homs and Palmyra. ISIL seized Palmyra in May 2015, was pushed out by a joint Russian-Syrian military campaign, but retook control of the ancient city in December when Syria government forces withdrew.
Convoys of ISIL fighters and weapons, including anti-aircraft guns, medium range artillery and small arms and ammunition, appear to be moving through the Syrian Badia.
The Badia is a large, sparsely populated desert steppe that links north-eastern and southern Syria with Western Iraq. The steppe also reaches into north-eastern Jordan.
Much of the Badia appears to be under de facto ISIL control, to the alarm of the Jordanian government and the Military Operations Command centre, or MOC, in Amman. The MOC is staffed by a group of international army and intelligence officers which have been supporting moderate rebels opposed to Mr Al Assad and, increasingly, helping direct a fight against ISIL in the south.
"The Badia is a fertile area for ISIL. If they can control it, it will be hard to get them out of there," said a senior rebel involved in operations in southern Syria.
The exact number of ISIL fighters in the area is unknown, but more than 2,000 were in the swathe of territory around Bir Qassab at the end of 2016, according to one rebel intelligence estimate. That number was confirmed by the Jordanian military adviser.
In the last two months, that number has swollen, they said.
The growing strength of ISIL in the area prompted an attack by the Royal Jordanian Air Force on February 3, when jets struck a site on the outskirts of Damascus, used to prepare car and truck bombs.
Two days after the raid, the Jordanian military said it had destroyed barracks, ammunition warehouses, vehicles and several ISIL fighters.
Although Jordanian forces have not confirmed the precise location of the targets, rebels familiar with the attack say the air strikes were in the Badia, to the east of Bir Qassab, and in the eastern Ghouta, a rebel-held zone on the eastern edge of Damascus.
It is thought to be the first time Jordanian forces have flown so close to Damascus since becoming embroiled in the conflict against ISIL, as Syria’s bloody civil war has spilled out of control. Previous Jordanian sorties have been in the more remote eastern desert region near the Iraqi border.

Source: The National