Activists and UK-based war monitor the Syrian Observatory for Human Rights (SOHR) confirmed that government troops and their allies had reached the western outskirts of the city amid fierce fighting on Tuesday.
Isis’ defences collapsed, SOHR said, allowing the army to dismantle the mines around the besieged Brigade 137 airbase, allowing besieged troops and advancing forces to reunite.
Footage shows Isis schoolgirl Linda Wenzel being captured in Iraq
Forces loyal to President Bashar al-Assad have made steady gains on the jihadist militants’ desert position for several months with help from Lebanon’s Hezbollah and Russian air support.
In the past few days, the pace at which the Syrian army has retaken territory has increased to lightning speed.
Russia’s Defence Ministry confirmed that a Russian warship in the Mediterranean had fired cruise missiles toward Isis targets in Deir Ezzor province on Tuesday, destroying a communications and command centre, ammunition depots and an armoured vehicle repair shop.
In pictures: Isis’ weapons factories
Liberating the city will mean relief for Deir Ezzor’s estimated 70,000 residents, who have been reliant on UN air drops of food, medicine and other supplies since fighting over the city broke out in late 2014.
Syrian media has said that civilians have already begun celebrating Isis’ defeat. Pictures and video widely shared on social media could not be independently verified.
Ousting Isis from Deir Ezzor will be the latest victory for Assad, who has made a string of gains against the militant group this year.
The jihadists are also under significant pressure in their de facto capital of Raqqa, south of Deir Ezzor, where a US-backed Arab and Kurdish alliance has retaken the Old City in a battle which has seen significant civilian casualties.
Isis lost control of its largest city, Mosul in neighbouring Iraq, in July.
The crumbling of Isis’ so-called caliphate is leading the militants to adopt increasingly desperate measures to hang on to their remaining territory and impose their rules on people under control.
New research from IHS Markit’s Conflict Monitor suggests that the jihadists are urging women to the front line as the number of available men decreases – a significant detour from their previous stance on appropriate roles for women.
Liberated from Isis, women burn their burqas and men shave off their beards
“Despite [Isis]’s claims to the contrary, urging women to seek an active role in combat is most likely an attempt to reduce the impact of severe manpower shortages caused by the decimation of male fighters, and a recruitment crisis,” said Ludovico Carlino, a senior analyst.
“While [Isis] has used female suicide bombers in the past, it has not done so in the concentration seen in Mosul,” he added. “It is as yet unclear whether the spike in female suicide bombings is simply a result of the final pockets of [Isis] resistance or women compelled by the group to execute those attacks, or whether it represents the beginning of a wider trend of female fighters willing to take part in the group’s battles.”
The latest issue of the group’s propaganda magazine Rumiyah has called on women to take up arms during the current “times of intense trials and extreme hardships”.
Even so, observers believe that Isis’s days as a land-holding force are numbered.
The organisation is expected to mount a fierce insurgency across both countries, however, and step up its terror attacks around the world.