An extensive earthen wall is being built around the besieged Sudanese city of el-Fasher and is intended to trap people inside, according to research from Yale University.
From satellite images, the university's Humanitarian Research Lab (HRL) has identified more than 31 km (19 miles) of berms - or raised banks - constructed since May in territory outside the city occupied by the paramilitary Rapid Support Forces (RSF).
El-Fasher, under siege for more than a year, is the last major foothold in Darfur for Sudan's army, which has been battling the RSF since April 2023.
The Sudan Doctors Network has told the BBC that the RSF has been intensifying its offensive there and deliberately targeting civilians.
Yesterday there was a shelling in a civilian area down in the city centre that ended up killing almost 24 civilians and injuring 55 people, among them five women, Dr Mohamed Faisal Hassan, from the medics association, told the BBC's Newsday programme.
The attacks on the central market and a residential area were deliberate and heinous, he said.
Three days ago they targeted one of the biggest hospitals in el-Fasher and resulted in a massive massacre of patients and medical staff.
BBC Verify states that both sides in the conflict have used berms as a defensive tool.
However, the analysis by Yale's HRL suggests that the RSF is creating a literal kill box around el-Fasher.
The HRL traced the construction of the earthen walls on a map of el-Fasher, revealing a complex of strategies aimed at tightening the siege.
While civilians strive to escape the conflict's grip, they face an increasingly dire situation marked by targeted violence and humanitarian access limitations.
With the ongoing wall construction, the RSF has also determined the tactical conditions necessary for their military goals.
The implications are grave; should El-Fasher fall to the RSF, it could lead to broader control in Darfur and potentially partition the country amid ongoing violence and humanitarian crises.
