The arid, sparsely populated wastelands between the Tigris and Euphrates rivers are the last refuge of the militants in Iraq after troops ousted them from both valleys and all urban areas.
The Hashed Al Shaabi released live footage from Siniyah in Saleheddin province of bulldozers clearing an earthen barrier to allow heavy armour to advance into the desert.
In July, the Iraqi army and Shiite paramilitaries retook Mosul, the country's second largest city.
Long lines of pick-up trucks waited to follow.
Islamic State's self-declared caliphate has swiftly collapsed since July, when USA -backed Iraqi forces captured Mosul, the group's de facto capital in Iraq, after a grueling battle that had lasted nine months.
That offensive culminated in the lightning recapture of the town of Rawa last Friday and saw Iraqi forces meet up with Syrian forces at the border.More news: The best time to leave for Thanksgiving trips
Extremists from IS - also known by its Arabic acronym Daesh - have mostly been pushed out of Iraq.
Iranian President Hassan Rouhani today declared "victory" over the Islamic State group in Iraq and Syria as the jihadists cling to just a few remaining scraps of territory.
Iran's Supreme Leader Ayatollah Ali Khamenei has said the victory over the Islamic State (IS) terrorist group in Iraq and Syria is a defeat of the U.S. in the region, a media report said.
On the Syrian side of the border, Daesh is under massive pressure too.
"We will completely secure the desert from all terrorist groups of ISIS and declare Iraq clean of those germs", said army Brigadier General Shakir Kadhim.
Iranian militias have helped Syrian President Bashar al-Assad's strengthen his position in the country since 2014.