Islamic State militants, routed from one urban stronghold after another in Syria, have recently been moving deeper into Syria's remote desert, where experts say they are regrouping and preparing their next incarnation.
The Sunni militants' self-proclaimed "caliphate" with its contiguous stretch of land — linking major cities such as Syria's Raqqa and Iraq's Mosul — may have been vanquished, but many agree this territorial defeat will not mark the end of IS.
Beyond the urban and inhabited areas lies the vast Syrian Desert, also known as Badiyat al-Sham, famous for its caves and rugged mountains. It encompasses about 500,000 square kilometers (200,000 square miles) across parts of southeastern Syria, northeastern Jordan, northern Saudi Arabia, and western Iraq.
The desolate landscape is a perfect hideout and a second home for many IS militants from the days before the birth of their caliphate. Experts estimate that hundreds of thousands of troops would be needed to mount search operations — and even more to put the desert under permanent control.
Once they melt into the desert, without an army of tens of thousands of supporters from dozens of countries, IS jihadis will resort to guerrilla-style attacks: scattered hit-and-run attacks and suicide bombings.
"They love fighting battles in the desert and they will go back to the old ways," said Omar Abu Laila, a Europe-based opposition activist originally from Syria's eastern province of Deir el-Zour, which lies in the heart of Badiyat al-Sham.