BEIRUT • With a sudden lunge through militant lines, the Syrian military and its allies yesterday came to within 3km of relieving the Euphrates city of Deir al-Zor, where the Islamic State in Iraq and Syria (ISIS) has besieged an army garrison and 93,000 civilians for years.
The advance on the eastern city marks another stinging setback for the once-triumphant ISIS, fast retreating in both Iraq and Syria as its self-declared caliphate crumbles.
Deir al-Zor's provincial governor said on Sunday he expected the army to reach the city by tonight.
"Islamic State is in confusion. There is no leadership or centralised control," said a commander in the military alliance supporting Syrian President Bashar al-Assad.
Hemmed in on all sides, ISIS is falling back on a last Euphrates stronghold downstream of Deir al-Zor in the towns of al-Mayadin and al- Bukamal near the border with Iraq.
But as it has lost its core territory - defeated in Iraq's Mosul and yielding street after street in its de facto Syrian capital of Raqqa - the ultra-hardline group has still been able to launch attacks in the West and maintain a threat in other centres such as Libya.
In ISIS-encircled Deir al-Zor, news of the army's approach prompted people to take to the streets to celebrate, governor Mohammed Ibrahim Samra said by phone. The city has been cut off since 2013, after rebel groups rose up against Mr Assad during the first flush of Syria's six-year war. ISIS overran rebel positions and surrounded the army's enclave in the city in 2014.
It was a major prize. Deir al-Zor is the centre of Syria's oil industry, a source of wealth to the group and a serious loss to Damascus. As the army has pushed east in recent months, oil and gas fields have once more fallen to the government.
During the long siege, the city has been supplied by air drops.
For Mr Assad, the weekend's lightning advance caps months of steady progress after government forces turned from their victory over rebels in Aleppo last December to push eastwards against ISIS.
As the army and its allies have forced other militant pockets to surrender, including an ISIS enclave on Syria's border with Lebanon a week ago, it has been able to transfer more troops to the desert campaign.
ISIS fighters and their families evacuated from that enclave as part of a surrender deal were escorted by the Syrian army and Hizbollah to east Syria, but have been stopped by a US-led coalition from reaching Deir al-Zor.
Ten of the original 17 buses are now stuck in no-man's land between pro-government forces and ISIS territory and six buses retreated back into government areas, the commander added.